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Proteomic analysis using electrospray liquid chromatography-mass spectrometry (ESI-LC-MS) has been used to compare the sites of glycation (Amadori adduct formation) and carboxymethylation of RNase and to assess the role of the Amadori adduct in the formation of the advanced glycation end-product (AGE), N(epsilon)-(carboxymethyl)lysine (CML). RNase (13.7 mg/mL, 1 mM) was incubated with glucose (0.4 M) at 37 degrees C for 14 days in phosphate buffer (0.2 M, pH 7.4) under air. On the basis of ESI-LC-MS of tryptic peptides, the major sites of glycation of RNase were, in order, K41, K7, K1, and K37. Three of these, in order, K41, K7, and K37 were also the major sites of CML formation. In other experiments, RNase was incubated under anaerobic conditions (1 mM DTPA, N2 purged) to form Amadori-modified protein, which was then incubated under aerobic conditions to allow AGE formation. Again, the major sites of glycation were, in order, K41, K7, K1, and K37 and the major sites of carboxymethylation were K41, K7, and K37. RNase was also incubated with 1-5 mM glyoxal, substantially more than is formed by autoxidation of glucose under experimental conditions, but there was only trace modification of lysine residues, primarily at K41. We conclude the following: (1) that the primary route to formation of CML is by autoxidation of Amadori adducts on protein, rather than by glyoxal generated on autoxidation of glucose; and (2) that carboxymethylation, like glycation, is a site-specific modification of protein affected by neighboring amino acids and bound ligands, such as phosphate or phosphorylated compounds. Even when the overall extent of protein modification is low, localization of a high proportion of the modifications at a few reactive sites might have important implications for understanding losses in protein functionality in aging and diabetes and also for the design of AGE inhibitors.

Our investigations on the discovery of novel natural metabolites using type II polyketide synthase gene probes (actI/III) yielded an unusual angucyclinone, oviedomycin (2), when applied to the oleandomycin (1) producer Streptomyces antibioticus ATCC11891. The novel natural product was produced using S. albus R(-)M(-) as a host strain, into which a cosmid containing the oviedomycin gene cluster was transformed. Its structure was elucidated by NMR spectroscopy and mass spectrometry.

A rapid extraction method has been developed for the quantitation of (Z,E)-propanethial S-oxide, the lachrymatory factor (LF), and other flavor chemicals in onion (Allium cepa) using gas chromatogr...

Air samples were collected at an urban (Chicago, IL) and a rural (University of Wisconsin at Green Bay, UWGB) site during February 1988 to determine concentrations and particle/gas distributions of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Geometric mean ΣPAHs of molecular weights ≥166 were 195 ng/m 3 in Chicago and 14 ng/m 3 at UWGB. Ratios among PAHs suggested that some labile compounds were depleted during atmospheric transport. Geometric mean ΣPCBs (45 congeners) were 1.3 ng/m 3 in Chicago and 0.13 ng/m 3 at UWGB. PCB profiles of most samples in Chicago and all at UWGB were skewed toward the lower molecular weight congeners, as in mixtures of Aroclors 1242 and 1254. Two Chicago samples showed a heavy PCB profile similar to Aroclor 1260. Apparent particle/gas partition coefficients (K p ) were well correlated with liquid-phase vapor pressures (po L ) within a class of compounds (PAHs or PCBs). PAHs were sorbed to a greater degree than PCBs for compounds of the same volatility. Slopes of log K p vs log p o L plots deviated from the expected value of -1 in Chicago, suggesting nonequilibrium effects. Aerosols at UWGB appeared to be closer to equilibrium with the gas phase, as indicated by slopes close to -1. Measured particulate percentages in the two locations were within a factor of 2 of those predicted by the Junge-Pankow adsorption model.

Two experimental techniques were used to test the hypothesis that mono- and non-ortho-substituted polychlorinated biphenyls (PCBs) are sorbed to urban aerosols to a greater extent than multi-ortho congeners of the same homolog. Particulate and gaseous PCBs in Chicago air were operationally defined by sampling with a glass fiber filter followed by a polyurethane foam trap. After separation from organochlorine pesticides, PCBs were fractionated into non-ortho, mono-ortho, and multi-ortho groups on an activated carbon-silicic acid column and determined by capillary gas chromatography (GC) with electron capture detection or GC/mass spectrometry. Within a homolog group (e.g., pentachlorobiphenyls), the percentage of particulate PCBs increased in the order : multi-ortho < mono-ortho < non-ortho. This order was explained for the most part by the lower liquid-phase vapor pressures (p° L ) of mono- and non-ortho-PCBs, although the non-ortho congeners 77 and 126 showed slightly enhanced sorption relative to expectations based on vapor pressure. To gauge the relative extent of sorption for PCBs having different numbers of ortho-chlorines, filters loaded with Chicago aerosols were exposed to gaseous PCBs at a constant temperature. Particle/gas partition coefficients (K p ) were inversely related to p° L , but distinct differences were seen among the ortho-chlorine classes. For a given value of log p° L , values of log K p increased in the order : multi-ortho < mono-ortho < non-ortho. A multiple linear regression model using log p° L and the dihedral angle between the biphenyl rings explained 98% of the variance in sorption.

Concentrations of hexachlorocyclohexanes (HCHs) in air and water were measured in order to estimate the direction and magnitude of gas flux across the air-water interface in the four lower Great Lakes. Samples were collected in Green Bay, Lake Michigan during June, 1989, and in lakes Michigan, Huron, Erie, and Ontario during Aug 1990. Green Bay water was undersaturated with respect to the air due to low surface water temperatures (6-11 o C) and a well-mixed water column, and the flux direction was from air to water for both α- and γ-HCH

An experimental system was designed to equilibrate urban air particulate matter on a glass fiber filter (GFF) with gas-phase organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs) at controlled temperature, humidity, and vapor concentrations. Particle-loaded filters (PLFs) were backed up by clean filters (CFs) to correct for gaseous semivolatile organic compound (SOC) adsorption to the filter matrix. Analysis of the CF indicated the presence of a complex mixture of alkanes and other organic compounds in addition to the OC pesticides introduced in the experiment