pubmed:abstractText |
The first committed enzyme in valine biosynthesis, acetolactate synthase, in the photosynthetic bacterium, Rhodopseudomonas spheroides, required added pyruvate (apparent Km--4.5 mM), Mg2+ (Km--1.01 mM), diphosphothiamine (Km--29.6 micrometer), flavin adenine dinucleotide, and a buffer pH of 7.2--7.4 for enzymatic activity. The synthase was affected by L-valine, an end-product inhibitor, in a competitive manner. The presence of acetolactate synthase, along with other earlier observed enzymes, completes the identification of the valine biosynthetic pathway in this photo-organotroph.
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