Phosphopyridoxyl derivatives, which are stable analogues of a substrate-coenzyme complex, are bound at the active site with great affinity. From a comparison of the interaction of a number of such compounds with the apoenzyme the delta G0 values for the binding of the substrate carboxy and phenyl groups and of the coenzyme aldehydic group were determined to be equal to (or more negative than) -3.8. -8.4 and -12.5kJ/mol (-0.9, -1.9 and -3kcal/mol) respectively; the delta G0 for the binding of the coenzyme phosphate group was shown to be more negative than -20.5kJ/mol (-4.9kcal/mol). Two features of the binding process of the coenzyme-substrate analogues to tyrosine decarboxylase have already been found in the case of tyrosine aminotransferase [Borri-Voltattorni, Orlacchio, Giartosio, Conti & Turano (1975) Eur. J. Biochem. 53, 151-160]: (1) in the binding of the substrate to the enzyme a significant fraction of the instrinsic delta G0 appears to be used for some associated endoergonic process; (2) the delta H0 and delta S0 of binding appear to be very sensitive indicators of the correct alignment of the substrate-coenzyme and analogues at the active site.

The binding of the coenzyme pyridoxal 5'-phosphate and analogues of the substrate-coenzyme complex to tyrosine decarboxylase

VOLTATTORNI, Carla;
1980

Abstract

Phosphopyridoxyl derivatives, which are stable analogues of a substrate-coenzyme complex, are bound at the active site with great affinity. From a comparison of the interaction of a number of such compounds with the apoenzyme the delta G0 values for the binding of the substrate carboxy and phenyl groups and of the coenzyme aldehydic group were determined to be equal to (or more negative than) -3.8. -8.4 and -12.5kJ/mol (-0.9, -1.9 and -3kcal/mol) respectively; the delta G0 for the binding of the coenzyme phosphate group was shown to be more negative than -20.5kJ/mol (-4.9kcal/mol). Two features of the binding process of the coenzyme-substrate analogues to tyrosine decarboxylase have already been found in the case of tyrosine aminotransferase [Borri-Voltattorni, Orlacchio, Giartosio, Conti & Turano (1975) Eur. J. Biochem. 53, 151-160]: (1) in the binding of the substrate to the enzyme a significant fraction of the instrinsic delta G0 appears to be used for some associated endoergonic process; (2) the delta H0 and delta S0 of binding appear to be very sensitive indicators of the correct alignment of the substrate-coenzyme and analogues at the active site.
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11562/7167
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact