Large ΔH^≠ and ΔS^≠ Values Obtained in Hydrolysis of α-Chymotrypsin or Catalase with α-Chymotrypsin

概要

論文の詳細を見る
α-Chymotryptic hydrolyses of globular proteins, α-chymotrypsin (Chym) and catalase (Cata), were examined kinetically at pH 7.8 and temperatures between 30 and 50℃. In both cases, the reactions followed second-order rate equations; -d[Chym]/dt=k(chy-chy)[Chym]^2 for the autolysis of Chym and -d[Cata]/dt=k(chy-cat)[Chym] [Cata] for the chymotryptic hydrolysis of Cata. From the Arrhenius plots, ΔH^≠/kJ mol^<-1> and ΔS^≠/JK^<-1> mol^<-1> were obtained as follows : for k(chy-chy)/dm^3 mol^<-1> s^<-1>, 270 and 681 at 30-44℃, and for k(chy-cat)/dm^3 mol^<-1> s^<-1>, 72.0 and 2.32 at 30-42℃, respectively. At higher temperatures than 45℃, the Arrhenius plots showed upward-concave curvatures in both cases. These extremely large activation parameters obtained for Chym autolysis and moderately large activation parameters obtained for Cata proteolysis are discussed in terms of deformation of the three-dimensional structures and the sites of proteolysis in the globular structures of the two enzymes.
公益社団法人日本薬学会の論文
1988-08-25