Squid muscle pyruvate kinase: Control properties in a tissue with an active α-GP cycle
1975; Elsevier BV; Volume: 52; Issue: 1 Linguagem: Inglês
10.1016/0305-0491(75)90139-x
ISSN0305-0491
AutoresKenneth B. Storey, Peter W. Hochachka,
Tópico(s)Adipose Tissue and Metabolism
Resumo1. Pyruvate kinase in squid muscle occurs as a single electrophoretic species with an isoelectric point at pH 5·9. 2. The enzyme activity is strongly affected by varying temperature and pressure. 3. Under normal assay conditions, saturation curves are Michaelis-Menten rectangular hyperbolas with Km values of 0·15 mM and 0·4 mM for phosphoenolpyruvate and ADP, respectively. 4. Fructose diphosphate and alanine do not affect the enzyme activity; even ATP is a rather poor inhibitor. 5. Control of the enzyme activity appears vested in NADH and citrate inhibition. NADH is non-competitive with P-enolpyruvate while citrate greatly reduces enzyme-substrate affinity and in its presence P-enolpyruvate saturation follows sigmoidal kinetics.
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