Search for Structural Basis of Interactions of Biogenic Amines with Human TAAR1 and TAAR6 Receptors

The identification and characterization of ligand-receptor binding sites are important for drug development. Trace amine-associated receptors (TAARs, members of the class A GPCR family) can interact with different biogenic amines and their metabolites, but the structural basis for their recognition by the TAARs is not well understood. In this work, we have revealed for the first time a group of conserved motifs (fingerprints) characterizing TAARs and studied the docking of aromatic (β-phenylethylamine, tyramine) and aliphatic (putrescine and cadaverine) ligands, including gamma-aminobutyric acid, with human TAAR1 and TAAR6 receptors. We have identified orthosteric binding sites for TAAR1 (Asp68, Asp102, Asp284) and TAAR6 (Asp78, Asp112, Asp202). By analyzing the binding results of 7500 structures, we determined that putrescine and cadaverine bind to TAAR1 at one site, Asp68 + Asp102, and to TAAR6 at two sites, Asp78 + Asp112 and Asp112 + Asp202. Tyramine binds to TAAR6 at the same two sites as putrescine and cadaverine and does not bind to TAAR1 at the selected Asp residues. β-Phenylethylamine and gamma-aminobutyric acid do not bind to the TAAR1 and TAAR6 receptors at the selected Asp residues. The search for ligands targeting allosteric and orthosteric sites of TAARs has excellent pharmaceutical potential.     

Formation of biogenic amines by proteolytic enterococci during cheese ripening

Six strains of Enterococcus faecalis and three strains of E faecium were investigated for their proteolytic activity and ability to decarboxylate the amino acids lysine, histidine, tyrosine, ornithine and phenylalanine. All strains tested displayed cell wall‐associated proteolytic activities, and three E faecalis strains displayed additionally extracellular proteolysis. None of the strains tested was able to form putrescine, histamine or cadaverine. Eight strains decarboxylated tyrosine, and two strains of E faecalis and one strain of E faecium formed phenylethylamine. Gouda cheese was produced from milk supplemented with two strains of E faecalis (10⁷ cfu ml⁻¹). Both strains were proteolytic and potent tyramine formers. Final viable counts of 10⁹ cfu g⁻¹ and tyramine concentrations of 477 mg kg⁻¹ were detected after a 12 week ripening period. © 1999 Society of Chemical Industry     

Anal sac secretion of the red fox,Vulpes vulpes; volatile fatty acids and diamines: Implications for a fermentation hypothesis of chemical recognition

Putrescine (1,4-diaminobutane) and cadaverine (1,5-di-aminopentane) were identified in the anal sac secretions of the red fox,Vulpes vulpes, and of the lion, Panthera leo. Anal sac secretion samples obtained over a period of 10 weeks by sampling from within each sac of each of 6 captive foxes were analyzed and putrescine, cadaverine, and volatile fatty acid compositions and secretion pH values recorded. A significant (P < 0.001) negative correlation of pH (range 6.5–9.4) with total volatile fatty acid concentration was observed. Secretion compositions are discussed in the context of a fermentation hypothesis of chemical recognition. Secretion samples could not be unambiguously assigned to particular foxes on the basis of simple comparisons of volatile fatty acid profiles alone. Composition differences were noted between secretions obtained at a given time from corresponding right and left sacs.     

THE METABOLISM OF PUTRESCINE,SPERMIDINE AND SPERMINE BY YEAST IN RELATION TO THE AVAILABILITY OF MAGNESIUM

During the lag period immediately after inoculation of yeast into a defined salts medium rapid changes in the internal concentrations of the oligoamines occurred when the medium was deficient in magnesium or high in calcium. Pronunced changes in the oligoamine content of yeast also occurred after inoculation into a range of worts and the extent of the effect appeared to depend on the magnesium content of the wort. The amount of magnesium in all the worts was much higher than was found to be saturating in a minimal medium and it therefore seems that the magnesium in worts is not freely available to the yeast cells. Putrescine was the only oligoamine found in wort and was present at about 1 mg/litre. The putrescine concentration in the wort always increased during fermentation and the period of most rapid increase corresponded to the period of decline in the internal oligoamine pools.     

Attraction of both sexes of Mexican fruit fly,Anastrepha ludens,to a mixture of ammonia,methylamine, and putrescine

Eight chemicals were evaluated in laboratory experiments as attractants for sugar-fed adult Mexican fruit flies. Ammonium bicarbonate, methylamine HCl, ethanolamine, pyrrolidine, putrescine, and monomethyl succinate were slightly attractive when tested singly. A mixture containing all eight chemicals was much more attractive than any of the individual chemicals. Through a series of experiments, a mixture of three of the chemicals was found that was at least as attractive as the original eight-component mixture. The final mixture consisted of ammonium bicarbonate, methylamine HCl, and putrescine in a 10101 ratio. Ratios were less important than actual concentrations of individual components over the range of component concentrations tested. The three-component mixture was equally attractive to male and female flies over at least a 1000-fold range of concentrations and was slightly more attractive thanTorula yeast over the upper 10-fold range in competing McPhail traps in a greenhouse flight chamber.     

Protein and Metabolite Analysis Reveals Permanent Induction of Stress Defense and Cell Regeneration Processes in a Tobacco Cell Suspension Culture

The secretome of a tobacco cell suspension culture was investigated by a combined proteomic and metabolomic approach. Protein analysis from 2-DE gels led to identification of 32 out of 60 spots from culture medium. Identified proteins were mainly involved in stress defence and cell regeneration processes. Among them three putative new isoforms, e.g. for chitinase, peroxidase and β-1,4-xylosidase were identified, not yet present in available protein databases for the genus Nicotiana. GC-MS analysis of time course experiments revealed significant changes for metabolites involved in energy transport, signalling and cell development. Among them, the most significant increase was found for putrescine in the medium of cultures entering the exponential phase. Results showed strong abundance of stress associated proteins and metabolites in the absence of elicitors or additional stress treatments.     

豆豉、腐乳蛋白质降解物限量标准研究

目的：测定豆豉、腐乳中包括挥发性盐基氮（total volatile basic nitrogen,TVB-N）值、三甲胺、硫化氢、生物胺在内的蛋白质分解产物含量,确定豆豉、腐乳中蛋白质的腐败程度,为生产更安全的豆豉、腐乳等发酵豆制品提供依据。方法：参考GB/T 5009.44-2003《肉与肉制品卫生标准的分析方法》、GB/T 5009.179-2003《火腿中三甲胺氮的测定》、GB/T 16489-1996《水质：硫化物的测定：亚甲基蓝分光光度法》及其他文献分别对样品中TVB-N值、三甲胺及硫化氢等进行测定。结果：豆豉中TVB-N值、总生物胺、腐胺、三甲胺及硫化氢的含量分别为8.20～372.72 mg/100 g、15.67～2 057.56 mg/kg、ND～276.03 mg/kg、0.26～10.43 mg/100 g及1.22～27.27 mg/kg;腐乳中的含量分别为95.33～652.94 mg/100 g、11.38～2 406.95 mg/kg、11.38～1 147.32 mg/kg、0.42～4.31 mg/100 g及0.27～3.72 mg/kg。结论：腐乳、豆豉中TVB-N、三甲胺、硫化氢、生物胺等腐败变质物质大量生成,影响此类食品的可食用性。可初步将TVB-N值、腐胺、总生物胺及三甲胺含量作为腐乳的腐败变质标志物;TVB-N值、总生物胺及三甲胺含量作为豆豉的腐败变质标志物,结合生产环节确定此类物质的限定值。     

The subcellular location of 4-aminobutyrate aminotransferase in Candida boidinii and its probable role in the breakdown of putrescine and spermidine

4-Aminobutyrate aminotransferase (EC 2.6.1.19) was elevated in activity by 20- to 40-fold in cells of the yeast Candida boidinii grown on spermidine, putrescine, 4-acetamidobutyrate and 4-aminobutyrate compared with activities detected in cells grown on ammonium, methylamine or 6-aminohexanoate, confirming previous suggesions that it plays a key role in polyamine breakdown. Other enzymes of the proposed route of polymine breakdown were found to be non-coordinately induced or derepressed during growth on spermidine or its putative breakdown intermediates. The enzyme was not sedimented from spheroplast lysates at 100 000 × g, and it is concluded that it is conclded that it is probably cytosoilc in its subcellular location (although the data do not exclude the possiblity of its being vacuolar).