Original scientific paper

Calorimetric Study of Ligand Binding to Fumarase

J. Kniewald ; Laboratory of Biochemistry, Technological Faculty, University of Zagreb, 41000 Zagreb, Croatia, Yugoslavia
P. Mildner ; Laboratory of Biochemistry, Technological Faculty, University of Zagreb, 41000 Zagreb, Croatia, Yugoslavia

Abstract

A microcalorimetric method has been used to study the binding
of inhibitors, succinate and citrate, to pig heart fumarase at single
conditions, i.e. 37 °c, pH 7.4 and I'/2 0.03, but by using three buffer
systems with different heats of ionization. Binding processes with
succinate and citrate were endothermic and the same general pattern
was obtained for the inhibitors used (~G0 - 37 or 38 kJ. mol-1).
It has been shown that 0.1 or 0.2 moles of H+ per mol of enzyme
was absorbed when the enzyme was saturated with succinate or
citrate, respectively. Binding processes in buffer systems with different
heats of ionization made possible the calculations of enthalpies
of binding (~H0 ' - 16.4 or 16.8 kJ moi-1) in a hypothetical buffer
system with zero. heat of ionization.

Keywords

Hrčak ID:

196355

URI

https://hrcak.srce.hr/196355

Publication date:

20.7.1977.

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