An enzyme catalyzing the synthesis of a specific substance. S. is limited, in the Enzyme Commission Report, to use as a trivial name for the ligases (EC class 6), which in turn are those synthesizing enzymes that require the cleavage of a pyrophosphate linkage in ATP or a similar compound. Reversal of lyase (EC class 4) reactions, producing a synthesis, is indicated (in trivial name s) by synthase; such reactions do not involve pyrophosphate cleavage. For individual synthetases, see the specific names.
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syn·the·tase 'sin-thə-.tās, -.tāz n an enzyme that catalyzes the linking together of two molecules esp. by using the energy derived from the concurrent splitting off of a pyrophosphate group from a triphosphate (as ATP) called also ligase
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syn·the·tase (sinґthə-tās) a term used in the trivial names of most enzymes of the ligase class [EC 6]; formerly part of the recommended name, it is no longer favored because of confusion with the term synthase and because it emphasizes reaction products rather than substrates. Cf. synthase.Medical dictionary. 2011.