Wheat germ carboxylase

During the formation of optically active acetoin, the two-carbon fragment derived from pyruvate must remain associated with the enzyme until it reacts with the carbonyl group of an acceptor molecule. The acceptor molecule may or may not be bound to the enzyme, but in either case it can approach the two-carbon fragment only in a single oriented manner, to yield an asymmetric product. The wheat germ carboxylase appears to hold its two-carbon fragment in an exposed position, so that aldehydes can approach from two directions one of these leads to (- -) and the other to ( —) acetoin. The two approaches are not equivalent. 

The highly purified wheat germ carboxylase of Singer carries out the simple decarboxylation of pyruvate to acetaldehyde and CO2. It can also synthesize AMC from pyruvate and acetaldehyde or form 2 moles of acetaldehyde, at a slower rate. The fact that this enzyme can form AMC from acetaldehyde alone indicates that this TPP-enzyme complex can activate acetaldehyde directly. This strongly suggests the formation of an acetaldehyde-TPP intermediate directly from acetaldehyde, which has the same capacity as that derived from the decarboxylation of pyruvate, to condense with a free acetaldehyde molecule to form AMC. 

Bio-Research Products Inc., was founded in 1975, and specialized in the isolation, purification and characterization of enzymes and proteins. The company is well known for its production of wheat germ phosphoenolpyruvate carboxylase (PEPC). Currently, it is involved in finished goods and raw material production, through a biomedical contract. Bio-Research Products runs custom services on enzymes, proteins production, diagnostic assays, and other goods for industry, governments, or academia. Bio-Research Products, Inc. also markets a number of enzymes and associated products, and carries out custom synthesis projects. 

Acetyl-CoA carboxylase has been purified from several plant tissues. In wheat germ, the BCCP and biotin carboxylase are associated with one fraction while the carboxyltransferase can be isolated independently (Heinstein and Stumpf, 1969). The carboxylase from chloroplasts has prokaryotic ... 

AMC is usually formed from 1 mole of pyruvate and 1 mole of acetaldehyde. Isotope experiments with labeled pyruvate indicate that the. acetyl portion of the AMC is always derived from the pyruvate. In other words, the active acetaldehyde is derived from the pyruvate. The simple carboxylases of yeast and wheat germ carry out this reaction. ... 

Hatch MD, Stumpf PK. Acetyl coenzyme A carboxylase and acyl coenzyme A-malonyl coenzyme A transcarboxylase from wheat germ. J Biol Chem 1961 236 2879-2885. 

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