Oxidation of amines by flavoproteins

Many flavoproteins catalyze the oxidation of primary and secondary amines, with the transfer of a hydride equivalent from a carbon-nitrogen bond to the flavin cofactor. Most of these amine oxidases can be classified into two structural families, the D-amino acid oxidase/sarcosine oxidase family and the monoamine oxidase family. This review discusses the present understanding of the mechanisms of amine and amino acid oxidation by flavoproteins, focusing on these two structural families.     

不利用丙酮酸的丙酮酸生产菌的选育

以光滑球拟酵母(Torulopsis glabrata)TP19为出发菌,经过UV和DES复合诱变选育出一株不利用丙酮酸的高产菌(TP204)。其摇瓶发酵产酸量和产酸率分别比原菌增加了26.4%和26.5%。在5 L罐上的产酸量和产酸率分别是70.23 g.L-1和64.6%,比原菌增加了5.7%和5.3%。     

Oxidation of furan fatty acids by soybean lipoxygenase-1 in the presence of linoleic acid

The interaction of furan fatty acids (F-acids) with lipoxygenase was investigated by incubation experiments of a synthetic dialkyl-substituted F-acid with soybean lipoxygenase-1. Originally the oxidation of furan fatty acids was assumed to be directly effected by lipoxygenase. It is now demonstrated that this reaction is a two-step process that requires the presence of lipoxygenase substrates, e.g. linoleic acid. In the first step linoleic acid is converted by the enzyme to the corresponding hydroperoxide. This attacks, probably in a radical reaction, the furan fatty acid to produce a dioxoene compound that can be detected unequivocally by gas chromatography-mass spectrometry.     

Biotechnological production of pyruvic acid

Pyruvic acid is an important organic acid widely used in the chemical and drug, as well as agrochemical, industries. Compared with the chemical method, biotechnological production of pyruvic acid is an alternative approach because of the low cost. An overview of biotechnological production of pyruvate, including direct fermentative production employing eukaryotic and prokaryotic microorganisms, production by a resting cell method and an enzymatic method as well as the recovery of pyruvate, is discussed. A multi-vitamin auxotrophic yeast strain, Torulopsis glabrata. has been used in the commercial production of pyruvate; emphasis is therefore placed on the mechanism and characteristics of pyruvate production by this strain.     

Regulation of store-operated calcium channels by the intermediary metabolite pyruvic acid

A rise in cytosolic Ca(2+) concentration is used as a key activation signal in virtually all animal cells, where it triggers a range of responses, including neurotransmitter release, muscle contraction, and cell growth and proliferation. A major route for Ca(2+) influx is through store-operated Ca(2+) channels. One important intracellular target for Ca(2+) entry through store-operated channels is the mitochondrion, which increases aerobic metabolism and ATP production after Ca(2+) uptake. Here, we reveal a novel feedback pathway whereby pyruvic acid, a critical rate-limiting substrate for mitochondrial respiration, increases store-operated entry by reducing inactivation of the channels. Importantly, the effects of pyruvic acid are manifest at physiologically relevant concentrations and membrane potentials. The reduction in the inactivation of calcium release-activated calcium (CRAC) channels by pyruvate is highly specific in that it is not mimicked by other intermediary metabolic acids, does not require its metabolism, is independent of its Ca(2+) buffering action, and does not involve mitochondrial Ca(2+) uptake or ATP production. These results reveal a new and direct link between intermediary metabolism and ion-channel gating and identify pyruvate as a potential signaling messenger linking energy demand to calcium-channel function.