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説明
Abstract 1. 1. The rate of formation of the purple itermediate of d -amino acid oxidase [ d -amino acid:O2 oxidoreductase (deaminating), EC 1.4.3.3] in the anaerobic reaction of this enzyme with its substrate was reduced by substitution of the α-hydrogen of the substrate for deuterium. This indicates that removal of the α-hydrogen of the substrate occurs prior to or in concert with the formation of the purple intermediate. The extent of the deuterium kinetic isotope effect differed for different substrates. 2. 2. The α-deuteration of the substrate affected neither the rate of conversion of the purple intermediate to the fully reduced enzyme nor the rate of oxidation of the purple intermediate with O2. 3. 3. The kinetic isotope effect on the catalytic oxidation of the substrate was less than that on the formation of the purple intermediate. This indicates that the purple intermediate formation partially determines the overall rate of the enzymic reaction, but the effect on the overall rate is thought to result merely from the effect on the process of the purple intermediate formation. The kinetic isotope effect on the catalytic oxidation was increased by decreasing the enzyme concentration. This may be interpreted to mean that the process of the purple intermediate formation is more rate controlling in the monomeric enzyme than in the dimeric enzyme.
収録刊行物
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- Biochimica et Biophysica Acta (BBA) - Enzymology
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Biochimica et Biophysica Acta (BBA) - Enzymology 321 54-71, 1973-09-01
Elsevier BV