| 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) |
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| 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) |
| f2 fragment | <immunology> A fragment of an antibody protein which includes the antigen-binding portions but not the Fc section. They can be produced by treating whole antibodies with proteases that will specifically cleave off the Fc section. (09 Oct 1997) |
| Fab fragment | The antigen-binding fragment of an immunoglobulin molecule, consisting of both a light chain and part of a heavy chain. Synonym: Fab piece. (05 Mar 2000) |
| Fc fragment | <immunology> The constant region on an immunoglobulin molecule. The area that is exactly the same on all antibodies. The region is found on the heavy chains and is not involved in binding antigens. (09 Oct 1997) |
| Klenow fragment | <molecular biology> Larger part of the bacterial DNA polymerase I (76 kD) that remains after treatment with subtilisin, retains some but not all exonuclease and polymerase activity. (18 Nov 1997) |
| fragment | A small part broken from a larger entity. (05 Mar 2000) |
| fragment reaction | A reaction used to assay the activity of peptidyl transferase. (05 Mar 2000) |