Oxidation products of amino acids and collagen.

Amino acids are known to react with oxidizing agents and some of the degradation products are less complex amino acids. In this study, 14 amino acids as well as fibrous corium collagen and epoxy resin-tanned collagen were reacted with a hydrogen peroxide or hydrogen peroxide-copper sulfate solution, and a number of amino acids were identified chromatographically which were not originally present. These results may explain the presence of several ninhydrin-reactive unknowns formed during hydrolysis of the product obtained by tanning fibrous corium collagen with an epoxy resin.     

The reactions of the sulfur-containing amino acids with phosphoric and sulfuric acids

Both cystine and cysteine react very differently toward 6.0 M phosphoric and sulfuric acids. With phosphoric acid, extensive decomposi tion occurs; with sulfuric acid, very little.Cystine, in phosphoric acid at 100 °C. produces hydrogen sulfide, free sulfur, cysteic acid, ammonia, alanine, serine, and pyruvic acid. Cysteine produces a similar series but with marked quantitative differences.Cystine, in sulfuric acid, is merely racemized.Methionine is largely demethylated by sulfuric acid under these conditions. It is practically inert toward phosphoric acid.The behavior of hair toward phosphoric and sulfuric acids is similar to that of cystine but is modified by reactions of other hydrolytic products.     

Stereoselective synthesis and characterization of new enantiomerically pure phosphoric acids

Starting from (R)‐6,6′‐dimethyldiphenyl‐2,2′‐dicarboxylic acid, a novel class of enantiomerically pure cyclic dialkyl phosphates was synthesized and properly characterized. The absolute configuration was determined by 2D NOESY experiments. The catalytic behavior of the new chiral Bronsted acids was investigated in the stereoselective addition of a silyl keteneacetal to aldimines. The Mannich‐type reaction was promoted in up to 94% yields and enantioselectivities up to 55%. On the basis of preliminary molecular mechanic calculations, a model of stereoselection was also proposed to explain the sense of the enantioselectivity observed in the reaction. Chirality 2010. © 2009 Wiley‐Liss, Inc.     

Inhibition of soil urease activity by amido derivatives of phosphoric and thiophosphoric acids

Summary A laboratory experiment was conducted to study inhibition of soil urease activity by amido derivatives of phosphoric and thiophosphoric acids. Results showed that derivatives with higher amido substitutions have greater inhibitory effect on urea hydrolysis in the soils used in our study. Triamides of phosphoric and thiophosphoric acids were found to be very effective inhibitors of soil urease. These compounds seem to have potential as fertilizer amendments for inhibiting soil urease activity and for improving the efficiency of nitrogen use from urea.     

Oxidation of corticosteroids to steroidal-21-oic acids by human liver enzyme.

An enzyme that oxidizes corticosteroids to acidic metabolites has been purified from postmortem human liver. The most rapidly oxidized substrate was 11-deoxycorticosterone (DOC). Other corticosteroids were oxidized at rates that were 10% or less of DOC. The products of DOC oxidation were 3, 20-dioxopregn-4-en-21-oic acid and 20-hydroxy-3-oxopregn-4-en-21-oic acid. The 20-keto acid was the predominant metabolite in all enzyme preparations. Keto acid and hydroxy acid were not interconverted. Enzyme activity was assayed by measuring the transfer of tritium from [21-3H]DOC to water. The enzyme is yellow, and has spectral maxima at 278 and 405 nm. Inhibition by o-phenanthroline suggests that it may be a metalloenzyme. Molecular weight was estimated at 74 000 +/- 8 000; a pH maximum occurred at pH 8-8.5. This enzyme may participate in the in vivo conversion of corticosteroids to the acidic metabolites that we have described previously (H.L. Bradlow et al. (1973), J. Clin. Endocrinol. Metab. 37, 811).     

Oxidation of fatty acids by Leishmania braziliensis panamensis

Heating cultures of Leishmania braziliensis panamensis (grown at 26 degrees C) to 34 degrees C for 1.5-12 h transformed the cells to an ellipsoidally shaped form. The heat treatment caused an increase in the rate of oxidation of both medium and long chain fatty acids but decreased the rate of oxidation of [1-14C]glucose. The rate of fatty acid oxidation continued to increase for times as long as 20 h after returning the cultures to 26 degrees C. In both the promastigote and heat-induced ellipsoidal forms, the ratio of 14CO2 release from [1-14C]laurate to that from [12-14C]laurate was generally larger than four, whereas this ratio from [1-14C]oleate relative to [10-14C]oleate was approximately two. These data show that metabolic and morphological differentiation begin after a short heat treatment and that some metabolic changes may continue even after the reverse transformation is initiated. The data also suggest that either the omega-terminal portion of the fatty acids is not completely oxidized to acetyl CoA and/or that there are two functional fatty acid oxidation pathways in Leishmania.