protogen


li·po·ic ac·id

(li-pō'ik as'id), A bacterial growth factor present in yeast and liver extracts; may be useful in the treatment of mushroom poisoning. Functions as the amide (lipoamide) cofactor in the disulfide (-S-S-) form in the transfer of "active aldehyde" (acetyl), the two-carbon fragment resulting from decarboxylation of pyruvate from α-hydroxyethylthiamin pyrophosphate to acetyl-CoA, itself being reduced to the dithiol form (that is, dihydrolipoic acid) in the process. Lipoic acid is also an essential component of other α-keto acid dehydrogenase complexes. Synonym(s): acetate replacement factor, ovoprotogen, protogen, protogen A, pyruvate oxidation factor, thioctic acid

protogen

(1) An obsolete term for a concentrate of natural substances, including lipoic acid, that is capable of sustaining the growth of Tetrahymena spp. 
(2) Thioctic acid, lipoic acid.