L-gulonolactone oxidase L-gulonolactone oxidase -gulonolactone oxidase (EC 1.1.3.8) is an enzyme that produces vitamin C, but is non-functional in Haplorrhini (including humans), in some bats, and in guinea pigs. It catalyzes the reaction of -gulono-1,4-lactone with oxygen to -xylo-hex-3-gulonolactone and hydrogen peroxide. It uses FAD as a cofactor. The -xylo-hex-3-gulonolactone (2-keto-gulono-gamma-lactone) is able to convert to hexuronic acid (ascorbic acid) spontaneously, without enzymatic action. The non-functional gulonolactone oxidase pseudogene (GULOP) was mapped to human chromosome 8p21 that corresponds to an evolutionarily conserved segment on either porcine chromosome 4 (SSC4) or 14 (SSC14). GULO produces the precursor to ascorbic acid, which spontaneously converts
Vitamin time it was shown that not all vitamins are amines, the word was already ubiquitous. In 1920, Jack Cecil Drummond proposed that the final "e" be dropped to deemphasize the "amine" reference, after researchers began to suspect that not all "vitamines" (in particular, vitamin A) have an amine component. In 1930, Paul Karrer elucidated the correct structure for beta-carotene, the main precursor of vitamin A, and identified other carotenoids. Karrer and Norman Haworth confirmed Albert Szent-Györgyi's discovery of ascorbic acid and made significant contributions to the chemistry of flavins, which led to the identification of lactoflavin. For their investigations on