164 ROBERT A. ALBERTV 



to show how these are being handled in the case of fumarase. The prospects 

 are encouraging, but quite a bit remains to be done before information about 

 the catalytic site will be obtained by the study of inhibitors. However, the 

 studies of the effect of pH on the fumarase reaction have shown that the en- 

 zymatic site may be considered to be a dibasic acid. The fact that it is the 

 intermediate ionized form which is catalytically active suggests that the en- 

 zymatic action involves the donation of a proton by one of these groups and 

 the acceptance of a proton by the other. What is needed in the study of in- 

 hibitors is kinetic data over a range of pH so that it will be possible to discuss 

 the affinity of a particular ionized form of the enzyme for the inhibitor and to 

 compare inhibitors with respect to their effects upon the ionization of groups 

 in the catalytic site. 



References 



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Alberty, R. A. 1954. Some mechanisms for the interpretation of the effects of pH and 

 buffer salts on a simple enzymatic reaction. J. Am. Chem. Soc. 76: 2494-2498. 



Alberty, R. A. 1955. The ionization constants of the heme-linked groups of hemoglobin. 

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Alberty, R. A. 1956. Kinetic effects of the ionization of groups in the enzyme mole- 

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Frieden, C. 1955. Kinetic studies of the enzyme fumarase. Ph D. Thesis. University 

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Frieden, C. and R. A. Alberty. 1955. The effect of pH on fumarase activity in acetate 

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Frieden, C, R. M. Bock and R. .■\. .\lberty. 1954. Studies of the enzyme fumarase. 

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Haldane, J. B. S. 1930. Enzymes. New York. Longmans, Green and Company. 



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Massey, V. 1951. The crystallization of fumarase. Biochem. J. 51: 490-494. 



