| quaternary carbon atom | An atom of carbon to which four other carbon atom's are attached. (05 Mar 2000) |
|---|---|
| one-carbon fragment | The formyl group or the methyl group that takes part in transformylation or transmethylation reactions; by means of these reactions, a group containing a single carbon atom is added to a compound being biosynthesised, adding a methyl group (as in thymidine formation), adding a hydroxymethyl group (as in serine biosynthesis), or closing a ring (as in purine formation). (05 Mar 2000) |
| one-carbon group transferases | <enzyme> A subclass of transferases that transfer chemical groups containing a single carbon. These include the methyltransferases, the hydroxymethyl and formyl transferases, the carboxyl and carbamoyl transferases, and the amidinotransferases. Registry number: EC 2.1 (12 Dec 1998) |
| two-carbon fragment | The acetyl group (CH3CO-) that takes part in transacetylation reactions with coenzyme A as carrier; commonly referred to as acetate or acetic acid, from which it is derived. (05 Mar 2000) |