Intermediates in the metabolism of m-carboxy-substituted aromatic amino acids in plants: Phenylpyruvic acids,mandelic acids,and phenylglyoxylic acids

Tracer experiments with ¹⁴C-labelled precursors in Iris × hollandica cv. Wedgwood, Roseda lutea L. and Reseda Odorata L. have demonstrated that 3-(3-carboxyphenyl)alanine and 3-(3-carboxy-4-hydroxyphenyl)alanine can be derived from the corresponding pyruvic acids, presumably by unspecific trans-aminations, and that (3-carboxyphenyl)glycine and (3-carboxy-4-hydroxy-phenyl)glycine can be derived from the corresponding phenylglyoxylic acids The glycine derivatives are derived from the alanine derivatives, and the corresponding mandelic acids are intermediates in these transformations. The corresponding phenylacetic acids are incorporated only slightly into the glycine derivatives, indicating that oxidation at the benzylic position in the C₆–C₃ compounds takes place early in the transformation. The corresponding cinnamics acids are not metabolized at all in the plants.     

Chemoenzymatic synthesis of surfactants from carbohydrates, amino acids, and fatty acids

The chemoenzymatic synthesis of new surfactants is reported; they were prepared from unprotected carbohydrates, amino acids, and fatty acids. This study pointed out the factors that govern the possibility to enzymatically bind the carbohydrate to the amino acid.     

Ion conductors derived from biogenic amines,bile acids,and amino acids

A family of conjugates has been synthesized from spermine, putrescine, lysine, gamma-aminobutyric acid, sarcosine, cholic acid, glycocholic acid, 3alpha,7alpha-dihydroxycholic acid, and 3alpha,12alpha-dihydroxycholic acid, based on a design principle previously reported (Bandyopadhyay, P., Janout, V., Zhang, L., Regen, S. L. (2001) J. Am. Chem. Soc. 123, 7691). Each of these conjugates was found to exhibit significant activity in promoting the transport of Na(+) across liposomal membranes derived from 1,2-dimyristoleoyl-sn-glycero-3-phosphocholine, and also from 1,2-dipalmitoleoyl-sn-glycero-3-phosphocholine. In all cases, plots of pseudo first-order rate constants, k(obsd) vs (mol % of ion conductor)(2) were found to be linear, indicating that transport-active dimers are involved and that only a small fraction of the conjugates are in an aggregated form. An operational comparison that has been made within this series of conjugates indicates that Na(+) transport activity and membrane selectivity have a moderate dependency on the composition and the structure of the ion conductor.     

Stimulatory effects of certain amino acids,sugars, organic acids,nucleic acids and metals on nitrate utilization by alkalophilic Bacillus

The growth of alkalophilic Bacillus no. A-40-2 with nitrate as the nitrogen source was highly stimulated by the addition of 0.1% of certain amino acids, sugars, organic acids, nucleic acids, or Fe²⁺ or Mn²⁺ at concentrations of 10 mM or more to the medium, resulting in maximum growth after 24 h. Other alkalophilic Bacillus strains also showed the same results. A decrease in the amount of nitrate in the medium was observed. The optimum pH of nitrate reductase was 7.5.     

Cholesterol, hydroxycholesterols, and bile acids

Although a variety of oxidation products of cholesterol occur in vitro, enzyme-catalyzed oxidations can occur at only 5 sites on the cholesterol molecule: C7alpha, C22R, C24S, C25, and C27. The genes coding for the synthesis of these enzymes were cloned, the tissue expressions of the mRNAs were identified, and the enzymes were characterized. The biologic properties of the hydroxycholesterol molecules that are initially generated and their metabolites are under study. Downregulation of cholesterol synthesis via the SREBP/SCAP regulatory pathway is common to the initial hydroxycholesterols, but more variations exist with respect to these intermediates functioning as ligands for the nuclear receptor LXRalpha. Because this receptor regulates the expression of cholesterol 7alpha-hydroxylase and ABC transporter proteins, hydroxycholesterols and their intermediate steroid metabolites modulate a number of biologic processes. Metabolism of 22S-hydroxycholesterol to steroid hormones differs from that of the other hydroxycholesterols which form mostly steroid acidic products, otherwise known as bile acids. In vivo estimates of their production rates in intact humans indicate that 24S and 25-hydroxycholesterol account for no more than 7% of total bile acid production per day. Current evidence indicates that cholesterol 7alpha-hydroxycholesterol generated in the liver is the major source of bile acids in older adults. It is also known that the cholesterol 27-hydroxylation pathway is the only one expressed in fetal and neonatal life. Precisely when the proportions contributed by these two metabolic pathways to bile acid synthesis begin to shift and the role of the cholesterol 27-hydroxylase pathway in reverse cholesterol transport mandate further study.     

Hydrocarbons,free fatty acids,and amino acids of sclerotia of Sclerotinia sclerotiorum

Summary Sclerotia of Sclerotinia sclerotiorum (Lib.) D By. were obtained from commercial pea-and bean-cleaning operations or grown on potato-dextrose agar and synthetic glucose-and sucrose-salts agar media. The crude fat (ether extract) content of sclerotia varied from 0.8 to 1.5%. Extraction and fractionation of the lipids followed by gas chromatographic analysis showed that sclerotia from pea cleanings contained one predominant hydrocarbon which was absent from sclerotia produced in the laboratory. Sclerotia from natural sources and grown in the laboratory contained a similar distribution of C₁₈ unsaturated free fatty acids, however, quantitative differences were noted. Palmitic, oleic and linoleic were the major free fatty acids of the laboratory-grown sclerotia while a high proportion of linoleic acid was also found in sclerotia from natural sources. Sclerotia were fractionated into water-soluble and water-insoluble fractions. After acid hydrolysis of the waterinsoluble fraction, both fractions were analyzed for amino acids. Twenty-one compounds, including 2 unknowns, were detected in the soluble fraction. The hydrolyzates contained 19 amino acids, including the same 2 unknowns. Two compounds tentatively identified as ornithine and -aminobutyric acid were found only in the water-soluble fraction. The relative amino acid composition of the water-insoluble fraction of sclerotia from various sources was fairly constant but the arginine content decreased on the synthetic media.     

Fatty acids,resin acids and phenols in Pinus muricata

Acetone-soluble extractives of “blue” and “green” strain Pinus muricata D. Don were found to consist of free and “combined” fatty acids, resin acids, and phenols. The composition of the extractives from the two strains was similar though “green” strain P. muricata contained more Δ^8(9),15 isopimaric acid than “blue” strain. This difference may be used to identify these muricata strains if the age of the wood precludes a monoterpene examination.     

Human absorption of fish oil fatty acids as triacylglycerols, free acids, or ethyl esters

The transient rise in plasma triacylglycerol fatty acids after single-dose ingestion of fish oil as triacylglycerols, free acids, or ethyl esters with linseed oil as an absorption standard was used to determine the relative absorption of fish oil fatty acids in eight men. As free acids, the fish oil fatty acids were well absorbed (greater than or equal to 95%). As triacylglycerols, eicosapentaenoic acid (1.00 g) and docosahexaenoic acid (0.67 g) were absorbed only 68% and 57% as well as the free acids. The ethyl esters were absorbed only 20% and 21% as well as the free acids. The incomplete absorption of eicosapentaenoic and docosahexaenoic acids from fish oil triacylglycerols correlates well with known in vitro pancreatic lipase activity.     

Interactions of an antitumor platinum compound with deoxyribonucleic acid, histones, L-amino acids, poly-L-amino acids, nucleosides and nucleotides

Interaction of cis-dichloro(dipyridine)platinum(II) (cis-PPC) with calf thymus DNA, calf thymus histone, l-amino acids, poly-l-amino acids, nucleosides, and nucleotides has been evaluated by equilibrium dialysis technics. At least a 28 % decrease in the association of cis-PPC with DNA occurs when the platinum compound is pre-incubated with l-amino acids. The greatest decrease in association is seen upon pre-incubation of the platinum compound with the free amino acids. Glut, Asp, Lys, Arg, and CySH, before the addition of a sack containing a solution of DNA. The low level of association between DNA and the amino acids tends to rule out competition between cis-PPC and amino acids for DNA association sites. cis-PPC was repelled from sacks containing positively charged poly-l-Lys, poly-l-Arg, and calf thymus histone; however, in the presence of poly-l-Glut and poly-l-Asp, cis-PPC associated with these negatively charged polymers to a considerable degree. Enhanced chloride dissociation from cis-PPC was observed in the presence of all of the amino acids and the nucleotides GMP, CMP, UMP, and TMP, but not in the presence of AMP or the nucleosides rG and dG. In the presence of calf thymus histone, the association of cis-PPC with calf thymus DNA was reduced by more than 50% at histone/DNA ratios of 0.8–1.0.These data suggest that cis-PPC or cis-Pt(II) may associate with electron-rich areas of not only nucleic acids and proteins but also with body pools of free nucleotides and amino acids. The presence of positively charged histones shielding DNA strands in vivo suggests that the most probable point of platinum-DNA association would be at de-repressed areas of DNA which are undergoing RNA synthesis. The aquated form of the platinum complex may also associate with acidic proteins which appear to be involved in the positive control of RNA synthesis and, as a result, this interaction may be of pharmacological significance.     

Nickel deficiency disrupts metabolism of ureides, amino acids, and organic acids of young pecan foliage

The existence of nickel (Ni) deficiency is becoming increasingly apparent in crops, especially for ureide-transporting woody perennials, but its physiological role is poorly understood. We evaluated the concentrations of ureides, amino acids, and organic acids in photosynthetic foliar tissue from Ni-sufficient (Ni-S) versus Ni-deficient (Ni-D) pecan (Carya illinoinensis [Wangenh.] K. Koch). Foliage of Ni-D pecan seedlings exhibited metabolic disruption of nitrogen metabolism via ureide catabolism, amino acid metabolism, and ornithine cycle intermediates. Disruption of ureide catabolism in Ni-D foliage resulted in accumulation of xanthine, allantoic acid, ureidoglycolate, and citrulline, but total ureides, urea concentration, and urease activity were reduced. Disruption of amino acid metabolism in Ni-D foliage resulted in accumulation of glycine, valine, isoleucine, tyrosine, tryptophan, arginine, and total free amino acids, and lower concentrations of histidine and glutamic acid. Ni deficiency also disrupted the citric acid cycle, the second stage of respiration, where Ni-D foliage contained very low levels of citrate compared to Ni-S foliage. Disruption of carbon metabolism was also via accumulation of lactic and oxalic acids. The results indicate that mouse-ear, a key morphological symptom, is likely linked to the toxic accumulation of oxalic and lactic acids in the rapidly growing tips and margins of leaflets. Our results support the role of Ni as an essential plant nutrient element. The magnitude of metabolic disruption exhibited in Ni-D pecan is evidence of the existence of unidentified physiological roles for Ni in pecan.     

Current topics in the biotechnological production of essential amino acids,functional amino acids,and dipeptides

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Binding of bile acids, organic anions, and fatty acids by bovine intestinal Z protein.

Z protein from bovine small intestinal mucosa was purified and its binding affinities for bile acids, organic anions, and fatty acids were compared with those of bovine hepatic Z protein. Purification of Z protein from intestinal and hepatic cytosol was performed by gel filtration, chromatofocusing, and hydroxyapatite chromatography. Both purified proteins had the same molecular weight (Mr 14,000) and eluted from a chromatofocused gel at about pH 10. Binding studies were performed by the competitive displacement of 8-anilinonaphthalene-1-sulfonic acid and by equilibrium dialysis. Binding affinities for bile acids, organic anions, and fatty acids were very similar between intestinal and hepatic Z proteins. Although the real physiologic role of Z protein remains to be further elucidated, these data indicate that intestinal Z protein participates in the mechanism of intracellular bile acid transfer in enterocytes.