title: Studies in valine biosynthesis. X. The acetolactate synthase from Rhodopseudomonas spheroides.
abstract: 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.
mesh_terms: D000093:Acetoin / Q000096:biosynthesis; D000095:Acetolactate Synthase / Q000378:metabolism*; D000693:Anaerobiosis; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism; D008027:Light; D008274:Magnesium / Q000378:metabolism; D007652:Oxo-Acid-Lyases / Q000378:metabolism*; D011773:Pyruvates / Q000378:metabolism; D012242:Rhodobacter sphaeroides / Q000378:metabolism*; D013835:Thiamine Pyrophosphate / Q000378:metabolism; D014633:Valine / Q000096:biosynthesis*
chemical_list: D011773:Pyruvates; D005182:Flavin-Adenine Dinucleotide; D000093:Acetoin; D000095:Acetolactate Synthase; D007652:Oxo-Acid-Lyases; D014633:Valine; D008274:Magnesium; D013835:Thiamine Pyrophosphate