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In this paper we report the synthesis of new azabicycloalkane scaffolds, which could be exploited to obtain cRGD-based bioconjugates that may find promising application for targeted drug delivery, theranostic, and general cancer-cell labeling. By exploiting a Hosomi-Sakurai intramolecular allylation reaction we efficiently converted a silylated aldehyde precursor into 7,5-fused lactam scaffolds endowed with an exocyclic double bond. The presence of the vinyl function should make it possible to conjugate bioactive compounds to selectively carry them to tumor sites. The optimized synthetic sequence allows the gram-scale preparation of the target scaffolds in a few steps and good 39% overall yield from readily accessible materials. The high reactivity of the exocyclic olefin moiety was ascertained by performing a Heck coupling reaction with 1-bromo-4-nitrobenzene, which gave the corresponding functionalized derivatives in good (80-91%) yields. [ABSTRACT FROM AUTHOR]

Abstract: So far, various approaches for phylogenetic analysis have been developed. Almost all of them put stress on analyzing nucleic acid sequences or protein primary structures. In this paper, we take the physicochemical properties of amino acids into account and introduce the hydropathy profile of amino acids into phylogenetic analysis. We find that this introduction is effectual and our method may be used to complement phylogenetic analysis. [Copyright &y& Elsevier]

Not all proteins form well defined three-dimensional structures in their native states. Some amino-acid sequences appear to strongly favour the disordered state, whereas some can apparently transition between disordered and ordered states under the influence of changes in the biological environment, thereby playing an important role in processes such as signalling. Although important biologically, for the structural biologist disordered regions of proteins can be disastrous even preventing successful structure determination. The accurate prediction of disorder is therefore important, not least for directing the design of expression constructs so as to maximize the chances of successful structure determination. Such design criteria have become integral to the construct-design strategies of laboratories within the Structural Proteomics In Europe (SPINE) consortium. This paper assesses the current state of the art in disorder prediction in terms of prediction reliability and considers how best to use these methods to guide construct design. Finally, it presents a brief discussion as to how methods of prediction might be improved in the future. [ABSTRACT FROM AUTHOR]

A 64-kDa membrane-bound glycoprotein (gp64) of the cellular slime mold Polysphondylium pallidum, is a putative cell/cell adhesion protein identified by adhesion-blocking antibody fragments (Fab). gp64 is expressed on the cell surface of growth-phase cells and seems to mediate cell/cell adhesion. This paper describes an improved purification method based on the lipophilic nature of this protein. A critical step in the purification method is to collect an insoluble top layer appearing during ammonium sulfate precipitation. The sequence of cDNA encoding gp64 and its deduced amino acid sequence have been determined previously. Based on cDNA sequence data, the structure of gp64 protein was analyzed: almost all amino acid compositions and partial amino acid sequences of lysyl-endopeptidase-digested peptides of gp64 were determined by protein analysis; all six asparagine- linked glycosylation sites (Asn-Xaa-Ser/Thr) in fact contain carbohydrates, and all 36 cysteine residues were involved in forming disulfide bridges. From these data, gp64 seems to be a unique protein among cell/cell adhesion proteins. [ABSTRACT FROM AUTHOR]

The Thr-102 mutant of yeast iso-l-cytochrome c is a useful system for the study of structure-function relationships in this important class of electron transfer proteins, but little is known about its structure. Furthermore, few assignments of individual amino acid residues in yeast iso-l-cytochrome c have been made by proton NM R. Here we report assignments for nearly half of the amino acids in the reduced Thr-102 mutant of yeast iso1-cytochrome c. We also report assignments for the oxidized Thr-102 mutant. While the crystal structure of the reduced iso-l-cytochrome c (N. B. not the Thr-102 mutant) has been reported, there is currently little structural information concerning its solution structure and none concerning the oxidized protein. There is also no information concerning the structure of either oxidation state of the Thr-102 mutant. Comparison of the chemical shift and NOE data for the reduced Thr-102 mutant and comparison of paramagnetic shifts for analogous residues between this mutant and horse-heart and tuna cytochromes c reveal that both the basic fold of Thr-102 yeast isoI-cytochrome c and the region around the site of the mutation are the same as those found in the latter two proteins. It is concluded that the results from structure function studies using the Thr-102 mutant will be applicable to eukaryotic cytochrome c in general. This knowledge allows us to proceed to a description of some mutants of yeast iso-l-cytochrome c in the next paper. [ABSTRACT FROM AUTHOR]

This paper experimentally verifies the idea presented earlier that the contact of nonpolar clusters located on the surface of protein molecules with water destabilizes proteins. It is demonstrated that protein stabilization can be achieved by artificial hydrophilization of the surface area of protein globules by chemical modification. Two experimental systems are studied for the verification of the hydrophilization approach. 1. The surface tyrosine residues of trypsin are transformed to aminotyrosines using a two-step modification procedure: nitration by tetranitromethane followed by reduction with sodium dithionite. The modified enzyme is much more stable against irreversible thermoinactivation: the stabilizing effect increases with the number of aminotyrosine residues in trypsin and the modified enzyme can become even 100 times more stable than the native one. 2. α-Chymotrypsin is covalently modified by treatment with anhydrides or chloroanhydrides of aromatic carboxytic acids. As a result, different numbers of additional carboxylic groups (up to five depending on the structure of the modifying reagent) are introduced into each Lys residue modified. Acylation of all available amino groups of α-chymotrypsin by cyclic anhydrides of pyromellitic and mellitic acids results in a substantial hydrophilization of the protein as estimated by partitioning in an aqueous Ficoll-400/Dextran-70 biphasic system. These modified enzyme preparations are extremely stable against irreversible thermal inactivation at elevated temperatures (65-98 °C); their thermostability is practically equal to the stability of proteolytic enzymes from extremely thermophilic bacteria, the most stable proteinases known to date. [ABSTRACT FROM AUTHOR]