Abstract
Cross-linkage of L-asparaginase (L-asparagine amidohydrolase, EC 3.5.1.1), a tetrameric enzyme from Escherichia coli, has been accomplished with dimethylsuberimidate. Approximately 60% of the enzyme is converted to dimers and higher oligomers. Associated with cross-linkage is a loss of enzymatic activity to about 17% of that found in the native enzyme. Using [1,8-14C]dimethylsuberimidate, 5 molecules of the suberimidate were shown to bind per monomer, a value corresponding to 25% of the lysine residues. The relative catalytic activity of the modified enzyme toward the alternative substrates L-glutamine, β-cyano-L-alanine, and 5-diazo-4-oxo-L-norvaline was essentially the same as that for the native enzyme.
ACKNOWLEDGMENTS The authors are indebted to Dr. P. K. Chang for her assistance in the preparation of dimethylsubermidate. The collaboration of Dr. Yung Pin Liu and Mr. J. Wagge in portions of this work is gratefully acknowledged. We are indebted to Dr. L. Stryer for bringing to our attention the potential use of dimethylsuberimidate in this problem and providing the initial supply of this compound.
- Copyright ©, 1972, by Academic Press, Inc.
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