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The loop between alpha-helix 6 and beta-strand 6 in the alpha/beta-barrel of ribulose-1,5-bisphosphate carboxylase/oxygenase plays a key role in discriminating between CO2 and O2. Genetic screening in Chlamydomonas reinhardtii previously identified a loop-6 V331A substitution that decreases carboxylation and CO2/O2 specificity. Revertant selection identified T342I and G344S substitutions that restore photosynthetic growth by increasing carboxylation and specificity of the V331A enzyme. In numerous X-ray crystal structures, loop 6 is closed or open depending on the activation state of the enzyme and the presence or absence of ligands. The carboxy terminus folds over loop 6 in the closed state. To study the molecular basis for catalysis, directed mutagenesis and chloroplast transformation were used to create T342I and G344S substitutions alone. X-ray crystal structures were then solved for the V331A, V331A/T342I, T342I, and V331A/G344S enzymes, as well as for a D473E enzyme created to assess the role of the carboxy terminus in loop-6 closure. V331A disturbs a hydrophobic pocket, abolishing several van der Waals interactions. These changes are complemented by T342I and G344S, both of which alone cause decreases in CO2/O2 specificity. In the V331A/T342I revertant enzyme, Arg339 main-chain atoms are displaced. In V331A/G344S, alpha-helix 6 is shifted. D473E causes disorder of the carboxy terminus, but loop 6 remains closed. Interactions between a transition-state analogue and several residues are altered in the mutant enzymes. However, active-site Lys334 at the apex of loop 6 has a normal conformation. A variety of subtle interactions must be responsible for catalytic efficiency and CO2/O2 specificity.

Substitution of Leu290 by Phe (L290F) in the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase from the unicellular green alga Chlamydomonas reinhardtii causes a 13% decrease in CO(2)/O(2) specificity and reduced thermal stability. Genetic selection for restored photosynthesis at the restrictive temperature identified an Ala222 to Thr (A222T) substitution that suppresses the deleterious effects of the original mutant substitution to produce a revertant enzyme with improved thermal stability and kinetic properties virtually indistinguishable from that of the wild-type enzyme. Because the mutated residues are situated approximately 19 A away from the active site, they must affect the relative rates of carboxylation and oxygenation in an indirect way. As a means for elucidating the role of such distant interactions in Rubisco catalysis and stability, we have determined the crystal structures of the L290F mutant and L290F/A222T revertant enzymes to 2.30 and 2.05 A resolution, respectively. Inspection of the structures reveals that the mutant residues interact via van der Waals contacts within the same large subunit (intrasubunit path, 15.2 A Calpha-Calpha) and also via a path involving a neighboring small subunit (intersubunit path, 18.7 A Calpha-Calpha). Structural analysis of the mutant enzymes identified regions (residues 50-72 of the small subunit and residues 161-164 and 259-264 of the large subunit) that show significant and systematically increased atomic temperature factors in the L290F mutant enzyme compared to wild type. These regions coincide with residues on the interaction paths between the L290F mutant and A222T suppressor sites and could explain the temperature-conditional phenotype of the L290F mutant strain. This suggests that alterations in subunit interactions will influence protein dynamics and, thereby, affect catalysis.

X-ray and electron diffraction studies of specific reaction intermediates, or reaction intermediate analogues, have produced a consistent picture of the structural mechanism of light-driven proton pumping by bacteriorhodopsin. Of central importance within this picture is the structure of the L-intermediate, which follows the retinal all-trans to 13-cis photoisomerization step of the K-intermediate and sets the stage for the primary proton transfer event from the positively charged Schiff base to the negatively charged Asp-85. Here we report the structural changes in bacteriorhodopsin following red light illumination at 150 K. Single crystal microspectrophotometry showed that only the L-intermediate is populated in three-dimensional crystals under these conditions. The experimental difference Fourier electron density map and refined crystallographic structure were consistent with those previously presented (Royant, A., Edman, K., Ursby, T., Pebay-Peyroula, E., Landau, E. M., and Neutze, R. (2000) Nature 406, 645-648; Royant, A., Edman, K., Ursby, T., Pebay-Peyroula, E., Landau, E. M., and Neutze, R. (2001) Photochem. Photobiol. 74, 794-804). Based on the refined crystallographic structures, molecular dynamic simulations were used to examine the influence of the conformational change of the protein that is associated with the K-to-L transition on retinal dynamics. Implications regarding the structural mechanism for proton pumping by bacteriorhodopsin are discussed.

Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) catalyses CO 2 assimilation in biology. A prerequisite for catalysis is an activation process, whereby an active site lysine is selectively carbamylated. The carbamyl group is then stablised by a metal ion, which in vivo is Mg 2+ . Other divalent metal ions can replace Mg 2+ as activators in vitro , but the nature of the metal ion strongly influences the catalytic activity of the enzyme and has a differential effect on the ratio of the carboxylation reaction and the competing oxygenation reaction. Biochemical studies show that calcium promotes carbamylation but not catalysis. To investigate the role of the metal in catalysis, we have determined two structures of the enzyme complexed with Ca 2+ and the transition state analogue 2-carboxy- d -arbinitol-1,5-bisphosphate (2CABP). One of the complexes was prepared by soaking 2CABP into crystals of the enzyme–Ca 2+ -product complex, while the other was obtained by cocrystallising the enzyme with calcium and 2CABP under activating conditions. The two crystals belong to different space groups, and one was merohedrally twinned. Both complexes show very similar three-dimensional features. The enzyme is carbamylated at Lys201, and requisite loops close over the bound ligands in the active site, shielding them from the solvent in a manner similar to the corresponding complex with Mg 2+ . However, there are subtle differences that could explain the particular role of Ca 2+ in these processes. The larger radius of the calcium ion and its reduced Lewis-acid character causes a significant increase in the required proton hop distance between the C3 proton and the carbamate on Lys201 in the calcium complex. This alone could explain the inability of calcium to sustain catalysis in Rubisco. Similar effects are also expected on subsequent proton transfer steps in the catalytic cycle. Here we also discuss the effect of metal substitution on the dynamics of the ligands around the metal ion.

Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the enzyme assimilating CO2 in biology. Despite serious efforts, using many different methods, a detailed understanding of activity and regulation in Rubisco still eludes us. New results in X-ray crystallography may provide a structural framework on which to base experimental approaches for more detailed analyses of the function of Rubisco at the molecular level. This article gives a critical review of the field and summarizes recent results from structural studies of Rubisco.

The crystal structure of an activated complex of ribulose-1,5-bisphosphate carboxylase/oxygenase from spinach and its product 3-phosphoglycerate has been determined to 2.2 A resolution. The structure is of the open form with the active site accessible to the solvent as observed in the structures of the activated ligand-free enzyme and the complex of the activated enzyme with the substrate ribulose-1,5-bisphosphate. Two molecules of 3-phosphoglycerate are bound per active site. The phosphates of both molecules bind approximately at the same position as the phosphates of ribulose-1,5-bisphosphate or the six-carbon intermediate analogue 2-carboxyarabinitol-1,5-bisphosphate, but one product molecule is swung out from the active site with its carboxylate group pointing toward solution. The present structure points to direct participation of the active site side chain of lysine 175 in later stages of catalysis. This possibility is discussed in the light of mutagenesis studies.

(1997). Business Ethics and Civil Society in Russia. International Studies of Management & Organization: Vol. 27, Ethics, Trust, and Control in Russian Organizations: Recent Developments, pp. 5-18.

The three-dimensional structure of the complex of ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco; EC 4.1.1.39) from spinach with its natural substrate ribulose 1,5-bisphosphate (RuBP) has been determined both under activating and non-activating conditions by X-ray crystallography to a resolution of 2.1 A and 2.4 A, respectively. Under activating conditions, the use of calcium instead of magnesium as the activator metal ion enabled us to trap the substrate in a stable complex for crystallographic analysis. Comparison of the structure of the activated and the non-activated RuBP complexes shows a tighter binding for the substrate in the non-activated form of the enzyme, in line with previous solution studies. In the non-activated complex, the substrate triggers isolation of the active site by inducing movements of flexible loop regions of the catalytic subunits. In contrast, in the activated complex the active site remains partly open, probably awaiting the binding of the gaseous substrate. By inspection of the structures and by comparison with other complexes of the enzyme we were able to identify a network of hydrogen bonds that stabilise a closed active site structure during crucial steps in the reaction. The present structure underlines the central role of the carbamylated lysine 201 in both activation and catalysis, and completes available structural information for our proposal on the mechanism of the enzyme.

Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyzes the carboxylation of ribulose 1,5-bisphosphate. The reaction catalyzed by Rubisco involves several steps, some of which can occur as partial reactions, forming intermediates that can be isolated. Analogues of these intermediates are potent inhibitors of the enzyme. We have studied the interactions with the enzyme of two inhibitors, xylulose 1,5-bisphosphate and 4-carboxyarabinitol 1,5-bisphosphate, by x-ray crystallography. Crystals of the complexes were formed by cocrystallization under activating conditions. In addition, 4-carboxyarabinitol 1,5-bisphosphate was soaked into preformed activated crystals of the enzyme. The result of these experiments was the release of the activating CO2 molecule as well as the metal ion from the active site when the inhibitors bound to the enzyme. Comparison with the structure of an activated complex of the enzyme indicates that the structural basis for the release of the activator groups is a distortion of the metal binding site due to the different geometry of the C-3 hydroxyl of the inhibitors. Both inhibitors induce closure of active site loops despite the inactivated state of the enzyme. Xylulose 1,5-bisphosphate binds in a hydrated form at the active site.

Commercial Operations on Earth conserve risk capital until revenue flow, then expand on profits or fail for lack of money. Lunar logistics distances are orders of magnitude (OOM) longer than previous trade routes on Earth, making risk capital conservation critical. Our company needs help on space communications, because the Lunar Trade Route distances to the moon have never occurred previously. The American military has 9 staff logistics people for every front line soldier. Lunar logistics must adapt normal commercial logistics on Earth into something that works in space over long distances. It sounds impossible, but affordable commercial logistics using innovation could reduce the cost of the lunar logistics and accelerate mankind’s movement off the planet. Lunar Transportation Systems, Inc. requires an innovative communications supplier affordable enough for our unmanned vehicles capable of growth for affordable logistics hardware delivering cargo to the lunar surface by starting small and later becoming reusable and profitable plus expanding on profits. Early innovation in logistics communication is a key to getting started toward low cost operations given the OOM increased trade route distances, especially with unmanned hardware. Communications hardware must start small, grow on profits rather than big upfront government funding and must be financeable by commercial or private sources. Our entrepreneurial venture believes a commercial space logistics opportunity exists for a small communications solution supporting a later logistics delivery system from LEO to the lunar surface. The concept will use existing commercial launch vehicles to LEO delivering our in-space vehicle hardware, propellant and payloads to LEO. The LTS communications requires a relatively inexpensive ride for our communications package on another satellite in a special orbit around Earth.

Trade routes are emerging from earth to other locations in space. Throughout history most trade routes have had intermediate transportation support bases along the route, especially at locations, where the type of transportation vehicle changes abruptly. The change from water to land creates a harbor, for example, which provides transportation services to both the types of transportation vehicles involved. Mature space trade routes will have similar facilities at locations or nodes in the transportation cycle related to support services, changes in transportation modes or vehicle designs and eventually at locations that are forced by the market economics of space commerce. These Propellant Depots and servicing facilities will become the new real estate of space commerce. Eventually a Lunar trade route will emerge and economics will govern the evolution of the trade route including the vehicles and the services provided by the transportation nodes to these vehicles. The economics of commerce will eventually govern with cost, location, transportation services, real estate values, and consumables propellants and other issues at these transportation nodes. Lunar trade route planning by business organizations is now considering locations in orbits around Earth, at liberation points, low lunar orbit and the surface of the moon. Propellant and other resources from lunar regolith on the surface of the moon may some day become less expensive in space than Earth sources, because the Earth’s gravity well will be considered a cost barrier. Eventually, the self-sustaining aspects of lunar resources will become more cost effective than materials from Earth. This paper proposes a commercial lunar transportation system and a logistics architecture with propellant depots designed for cost effective early growth as the market emerges, but capable of sustainable growth over 50 or more years including financing by private sector partners. The initial space logistics system will be capable of round-trip cargo transportation in support of lunar resource recovery and lunar surface operations. Experience with trade routes to and from natural resource recovery sites in remote areas on Earth can provide lessons learned and give some insight into the dangers of underestimating the importance of logistics operations. The paper’s suggests various locations for propellant depots in space and learns from remote resource recovery sites on Earth including PPP financing. The planning and control of the flow of goods and materials to and from the moon’s surface may be the longest and most complicated logistics challenge yet attempted by mankind. If a single logistics system does not work as expected, the price paid can be substantial. An initial propellant depot is discussed including the buildup and evolution into increased capabilities and expanded markets. The trick is to duplicate the success Big Oil has had in using risk money ($20 billion) in resource recovery ventures like the North Slope of Alaska to provide a profitable return. Big Oil did not commit their risk money to develop logistics

Space commerce is emerging around the Earth orbit and the moon. Commercial Space logistics will help supply these new industries. The Space Solar Power (SSP) industry brings with it some significant cost incentives and climate change opportunities. Ultimately, large solar collectors will transmit energy 24/7 to an Earth that has used most other sources of stored energy. Later these collectors will be 60% less expensive to build after the full impact of lunar resources is available. Available commercial transportation support is the key to lower space logistics costs. Cost reduction is the objective in this paper’s concept investigation of unmanned logistics transportation hardware. Cost reduction is very common and encouraged in commercial projects financed by private sources, but somewhat uncommon in space projects financed upfront by governments using taxpayer sources. The objective is to bring down the cost of the future Space Solar Assembly industry transportation to orbit to a level that space solar power begins to appear on popular energy and climate change lists of solutions and is implemented. Both the reusable launch vehicle (RLV) with 50% cost reduction and the heavy lift side-mount Shuttle Cm are within our grasp as a nation with the technology and aerospace leadership currently in hand. Eventually a Lunar trade route will emerge and economics will govern the evolution of transportation hardware on these off planet trade routes. Two trade routes will exist, one to LEO for the assembly of Space Solar Power (SSP) Collectors with heavy lift capability and second, a route to and later from the moon capable of transporting lunar materials for the fabrication of SSP in Earth orbit. Each route is not about new vehicle hardware, but how innovative these vehicles can be in reversing the upward spiral of space transportation cost. The planning and control of the flow of goods and materials to and from the moon’s surface may be the longest and most complicated logistics challenge yet to be attempted by mankind. The price paid, if a single logistics system does not work well, is significant. Innovation and lessons learned are discussed and trade route transportation solutions proposed. Innovation leads to cost reduction, and minimizing the early risk money Public Private Partnerships (PPPs) could help stimulate private financing. The proposed launch hardware innovation expands the External Tank, changes the shuttle orbiter into an unmanned carrier that becomes part of an SSP truss component in orbit. A reusable launch vehicle spearheads the lunar development with a smaller RLV with 50% cost reduction and delivers Lunar Transportation Systems payloads to LEO to start the trip to the moon. Later these same LTS payloads use an advanced ion engine on a reusable lunar cycler to deliver LTS payloads to LLO. Private financing demands a series of financial holidays or outflows of profits periodically to ease the risk and allow private investors to enter and exit at will. Commercially, this new lunar logistics route permits capability and technology growth as the market grows, offers affordable transportation for the commercial sector and the later recovery of lunar resources. After NASA and other countries move on to other destinations

The Public Private Partnership (PPP) is an administrative agreement uniting government and private interests on a focused project to reduce the financial burden of each, and to produce a commercial operation with the government’s share being a stimulator rather than a complete drain on taxpayers. The full force of private financing has impacted only a few commercial space endeavors, e.g., communication satellites and emerging space tourism. Large segments of space operations such as exploration, heavy lift, space logistics, off-planet assembly, and recovery of planetary resources could attract substantial private funds through properly structured PPPs. Furthermore, countries without the technologies to conduct separate space projects could participate, which has never before been possible. Mankind currently needs and wants some things that may be possible and affordable in the space environment. Sophisticated technologies and materials currently used in medicine, automobiles, computers, and textiles may have spin-in potential for space applications. Similarly, the transfer of space technology, expertise, and/or facilities to the commercial sector for private purposes, which previously has been performed at the end of a government program, could occur at the initiation of a PPP development cycle that would include interrelated goals and milestones for public and private participants. This would allow identifying dual-use opportunities and improving technologies based on non-space sector (i.e. real market) feedback. Also, other non-space technologies in energy, bio-tech, sensing / instrumentation, etc. could be considered during early PPP planning for possible alignment of their development with space applications. An opportunity may exist in the energy field by collecting the rays of the sun off planet and transmitting this energy to Earth antennas for distribution in the power grids of countries, without fossil fuel damaging Earth’s atmosphere. Emerging nations require energy for their industrialization. A recent study by the National Security Space Office (NSSO) suggests an outline plan for the creation of a commercial avenue toward a space based solar power alternative for power from space. Oilrich nations look for investments capable of long-term profits to bridge the revenue gap in the future after peak oil revenues. Space operations financed jointly by public and private groups with coordinated interests would accelerate space exploration, and thus reap its humanitarian benefits sooner. Our planet requires global solutions to critical problems in energy, global warming, food production, health, and other areas that can benefit from the increased cooperation and available financing associated with PPP relationships.

The moon is the first trade route beyond Earth and logistics will be a major spacecraft operation for the rest of time. An Earth trade route is a sequence of pathways and stopping places used for the commercial transport of cargo. Trade routes can be over land or water and become commercial and cost effective. Space trade routes use neither land nor water, but will evolve toward the most cost effective solutions in commercial space operations. Space transportation hardware and communication innovation coupled with technology development will evolve toward a commercial vehicle. Vehicle software on-board is the innovation key and the software maintenance is via the Internet upgrade model. LTS develops hardware for the 50-year evolution of logistics with increments from an early 800 kgs to later massive mining equipment delivered. The quicker the route economics evolve to orders of magnitude in cost reduction, the faster commercial development is realized. This paper offers a commercial perspective to new lunar transportation routes and proposes a logistics innovation that is designed to have sustainable growth over 50 years, financed by private sector partners and capable of cargo transportation in both directions with NASA cooperation with commercial lunar logistics and resource recovery operations. Communications and on-board software uses today’s technology and the internet software upgrading to achieve plug and play flexibility with the ability to use multiple vehicle and platform systems as individual communication nodes. The paper’s perspective is a commercial entrepreneurial business operation created by a startup team with previous commercial space experience, where previous innovation reduced costs and stimulated commerce with lessons learned from over $20B in private money in Alaskan Oil development, which had, for example, four different logistics transportation systems, but none actually worked successfully all the time even with early risk money of $20 billion. The development of the moon can build on mankind’s successes in remote logistics bases on Earth and learn the commercial financing of Public Private Partnerships to stimulate the billions in private sector funds to recover lunar resources using affordable commercial transportation along side government transportation in a cooperative manner. The moon is 50 times more remote than Alaska, and many times more expensive, so the proposed commercial lunar transportation architecture uses new innovations for modularity and flexibility leading to reduced development and logistics costs, provide a faster development schedule, and accelerate the ability to evolve. Commercial innovation can bring an ability to test many directions of space operations and provide multiple avenues, potentially leading to cost reduction. Commercially, innovation in communications and software updating procedures for off-planet hardware is important to the success of our commercial reusable operations. This new lunar logistics route permits capability and technology growth as the market grows, offers affordable transportation for the commercial sector and the later recovery of lunar resources. This allows NASA to move beyond the moon to Mars and further with an “in place” commercial logistics system able to service, stimulate and sustain mankind’s lunar commercial market environment.

Commercial mining towns on Earth become cities. Company towns need commerce to drive the growth and economy of early space colonies. Water is an early resource for camp consumables plus propellant export sales from asteroid mining operations at proposed burned out comets with water methane ice cores for sustainable growth over 50 years, financed from profits and capable with affordable logistics to support resource recovery. One co‐author's perspective includes remote resource recovery sites on Earth. Other co‐authors' experiences include architecture, lunar habitation, and architectural space colony concepts. This paper combines these experiences to propose commercial opportunities possible as mankind moves beyond one planet. Alaska's North Slope commercial history indicates that different multiple logistics transportation systems are required to reduce the risk to humans and families moved in before the oil flowed. Commercial enterprises have risked $20 billion and spent hundreds of billions in private money after profits were created. The lessons learned are applied to a burned out comet designated Wilson‐Harrington (1979) and explores the architecture for early living within the burned out comet disk created from ice recovery and later sealed with an expected methane ice interior. Considered is the recovery of the resources, the transport of water back to Earth orbit or L‐1, plus later the development of more comfortable space colony living. Commercial markets produce cities on Earth and the same can happen on Space Colonies. The key is an “in place” affordable commercial logistics system that can service, stimulate and sustain a 50‐year commercial propellant market.

Space transportation has evolved to entrepreneurs offering affordable transportation services to LEO. Society expects space tourism to produce low costs quickly, but entrepreneurs need the larger commercial transportation markets to raise the private money to build the orbital vehicles. Early heavy cargo is the logistics model of remote bases on Earth and is likely to be similar for off planet remote bases. Public Private Partnerships (PPP), (Norment, 2006) and other alliances with governments offer new transportation markets and combines private funding with government markets to accelerate the movement of mankind into space, (Kistler, 2004a). Entrepreneurs bring change like a multitude of innovation, changes to the traditional aerospace industry status quo, commercial market forces and the lowering of the cost of transportation to orbit. Within PPPs, government stretches space budgets, increases vehicle innovation without cost and gains cost advantages of larger markets. Examples of PPPs show some opportunity for change in space commerce is possible, (Stainback, 2000 and Spekman, 2000). Some of the items entrepreneurs bring include innovation in hardware, a maturing of the normal market forces such as the pressures from buyers and sellers rather than those from government planners or from regulation. Launch costs are high, society wants orbital hotels and current/future markets are not emerging because of high transportation costs. The paper proposes a new approach with examples, because mankind has taken a long time to transition from expendable launch vehicles to newer more affordable launch innovation and may require the introduction of new innovative approaches.

The transportation market from earth to and from low earth orbit has evolved to the emergence of commercial entrepreneurs hoping to offer transportation services to general public. Everyone expects space tourism will produce low costs quickly, but entrepreneurs need the larger commercial transportation markets to raise the private money to build the orbital vehicles. The Public Private Partnership (PPP) combines private funding with government markets to accelerate the movement of mankind into space. Entrepreneurs bring a multitude of innovation, changes to the traditional aerospace industry status quo and the lowering of costs to the high cost of transportation to orbit. In PPPs Government stretches space budgets, increases vehicle innovation without cost and gains cost advantages of larger markets. Examples of PPP show some of the power for change in space possible.

Someday commercial lunar transportation will exist. What would the commercial lunar transportation firm look like if it were available today or were to emerge in the future? It would start small and attempt to grow on revenues to minimize up-front costs. It would separate and focus on the 99% unmanned cargo rather than the 1% human cargo, understanding the difference in cost to satisfy the requirements of each type of mission. It would use the space adventure tourist as the sizzle of the steak they are selling. It would have expansion and evolutionary growth milestones that could be financed by private capital with incremental returns on investment. It would attempt to only meet 80% of early government requirements rather than the 20% that cost the most money to develop. It would offer incremental payload increase capability to minimize the up front cost. It would use a team approach with equity partners drawn from aerospace, finance, customer, industrial and international organizations. It would have a start-up team containing members with a history of developing previous successful space ventures plus on-loan participants from NASA, finance, international and commercial customer prospects. It would focus on unmanned, non-critical cargo from government customers and innovative cargo from entrepreneurs to realistically prove the reliability of the systems used before manned missions are attempted. It would attempt to generate interest from international, customer and finance to broaden its hardware cost options, increase its market base and enhance private financing avenues. It would have a commercial nuclear option well in mind and on the team, so it fits within the lunar transportation node system at the right time and is available for future destinations. It will have already determined that Helium3 is worth $6 billion/ton on earth to specific team customers and might impact global energy strategies including the need for oil. It will understand previous remote resource development locations on earth, like the North Slope oil and remote mining, to understand the economic drivers, like inbound tonnage to earth will eventually far exceed outbound tonnage. Such commercial companies exist today, but may not know it or realize the potential of the Moon, Mars and Beyond initiative. NASA can stimulate this emerging entrepreneurial sector with the potential of their Space Exploration Program.

The Uppsala Electron Density Server (EDS; http://eds.bmc.uu.se/) is a web-based facility that provides access to electron-density maps and statistics concerning the fit of crystal structures and their maps. Maps are available for approximately 87% of the crystallographic Protein Data Bank (PDB) entries for which structure factors have been deposited and for which straightforward map calculations succeed in reproducing the published R value to within five percentage points. Here, an account is provided of the methods that are used to generate the information contained in the server. Some of the problems that are encountered in the map-generation process as well as some spin-offs of the project are also discussed.

The crystal structure of Rubisco (ribulose 1,5-bisphosphate carboxylase/oxygenase) from the unicellular green alga Chlamydomonas reinhardtii has been determined to 1.4 A resolution. Overall, the structure shows high similarity to the previously determined structures of L8S8 Rubisco enzymes. The largest difference is found in the loop between beta strands A and B of the small subunit (betaA-betaB loop), which is longer by six amino acid residues than the corresponding region in Rubisco from Spinacia. Mutations of residues in the betaA-betaB loop have been shown to affect holoenzyme stability and catalytic properties. The information contained in the Chlamydomonas structure enables a more reliable analysis of the effect of these mutations. No electron density was observed for the last 13 residues of the small subunit, which are assumed to be disordered in the crystal. Because of the high resolution of the data, some posttranslational modifications are unambiguously apparent in the structure. These include cysteine and N-terminal methylations and proline 4-hydroxylations.

Activation of ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco; EC 4.1.1.39) by CO2 involves carbamylation of Lys 201 and the subsequent binding of a magnesium ion to complete the active site. The refined crystal structure of activated Rubisco shows that the magnesium ligands are Asp 203, Glu 204, the carbamate of Lys 201, and three water molecules. Structural differences between the unactivated and activated forms are minimal. Substrate binding replaces water ligands around the metal and triggers substantial structural changes in loops covering the active site. This leads to a contraction and tightening of the structure of the large subunits with the movements transmitted to and modulated by the small subunits.

GLOBAL OUTPOST, Inc., in cooperation with NASA, proposes to place a Space Shuttle External Tank (ET) in orbit for commercial purposes. The OUTPOST External Tank derived platform discussed in this paper is designed to service a commercial market and will also be available for governmental use. The platform requires power for its operation and will sell power to customers as one of 68 different commercial services offered. A number of alternatives for power systems are under study. The company expects to purchase a power subsystem from the available alternatives. The proposed facility will require 4 to 10 kW of power and remain in orbit for five or more years. The plan will combine private sector funding with NASA assistance to create a business location in orbit. While the ET normally falls just short of orbital velocity, it can be placed in orbit with little additional energy. The platform proposed is a minimum cost, man visited facility aimed at attracting commercial ventures seeking a low cost way to us...

Cristallisation dans les groupes P2 1 /n et P2 1 /c respectivement. Coordination plan carre autour des atomes Cu dans les deux cas

Drew Middleton, senior military correspondent for the New York Times, has written that relationships between commanders and the media in World War II were marked by mutual trust and confidence, because of the imposition of censorship. The central hypothesis (H1) was that military officers would be more trusting of the media in a censorship environment, with null hypothesis (H0) that censorship would have no affect on attitudes. Two sample groups of Army generals and colonels were tested by attitude response survey (75%) return, with half asked to respond as if they were in a censorship imposed war theater. Data was objectively and subjectively analyzed. H1 was supported and H0 was rejected. Open-eneded comments revealed an overall distrust of the media with bitterness over median performance in Vietnam. Many showed a respect for First Amendment ideals, but favored imposing censorship in wartime. Most respondents indicated that total honesty with the press is always best, but some acknowledged that the military occasionally tries to deceive the media for its own purposes.

Cristallisation dans les groupes P2 1 /n et P2 1 /c respectivement. Coordination plan carre autour des atomes Cu dans les deux cas