| hemiacetal | RCH(OH)OR', a product of the addition of an alcohol to an aldehyde (an acetal is formed by the addition of an alcohol to a hemiacetal). In the aldose sugars, the hemiacetal formation is internal and labile, brought about by the 4-OH or 5-OH attack on the carbonyl O, yielding the furanose or pyranose structures; the hemiacetal forms of the sugars are involved in all polysaccharides, as glycosyls or glycosides. See: hemiketal, acetal. (05 Mar 2000) |
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| versiconal hemiacetal acetate esterase | <enzyme> Converts versiconal hemiacetal acetate to versiconal; the first step in biosynthesis of versicolorin b and versicolorin a Registry number: EC 3.1.1.- Synonym: vha esterase (26 Jun 1999) |
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