Sie befinden Sich nicht im Netzwerk der Universität Paderborn. Der Zugriff auf elektronische Ressourcen ist gegebenenfalls nur via VPN oder Shibboleth (DFN-AAI) möglich. mehr Informationen...
Heat stabilization produced by protein-protein association. A differential scanning calorimetric study of the heat denaturation of the trypsin-soybean trypsin inhibitor and trypsin-ovomucoid complexes
Ist Teil von
The Journal of biological chemistry, 1975-03, Vol.250 (6), p.1966-1971
Ort / Verlag
United States: American Society for Biochemistry and Molecular Biology
Erscheinungsjahr
1975
Link zum Volltext
Quelle
Free E-Journal (出版社公開部分のみ)
Beschreibungen/Notizen
The irreversible thermal denaturation of the association complexes of bovine beta-trypsin with soybean trypsin inhibitor or
ovomucoid was observed with a differential scanning calorimeter. Association of trypsin with either inhibitor results in increased
heat stability. The largest effect is observed with beta-trypsin and soybean trypsin inhibitor. At pH 6.7, first order rate
constants (s-1) for denaturation at 72 degrees, determined at a heating rate of 10 degrees per min, are: beta-trypsin, 30
times 10-3; soybean trypsin inhibitor, 9 times 10-3; trypsin-soybean trypsin inhibitor complex, 0.4 times 10-3. Under equivalent
conditions, rate constants for ovomucoid and trypsin-ovomucoid complex are 4 times 10-3 and 1 times 10-3 s-1, respectively.
These changes in rate correspond to heat stabilization of trypsin equivalent to an increase of 16 and 9 degrees, respectively,
in its observed denaturation temperature. Rate constants determined for beta-trypsin and trypsin-soybean trypsin inhibitor
complex are independent of heating rate; those for soybean trypsin inhibitor and ovomucoid are a function of heating rate.
This suggests that predenaturational conformational alterations may be important steps in the denaturation of the inhibitors.
Activation energies for denaturation of the complexes and their components are all similar, averaging 70 kcal per mol. The
large activation energies observed suggest that denaturation of the complexes is not rate-limited by their dissociation.