Modification of an essential arginine of carbamate kinase |
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Authors: | RP Pillai M Marshall JJ Villafranca |
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Institution: | 1. Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802 USA;2. Department of Physiological Chemistry, University of Wisconsin, Madison, Wisconsin 53706 USA |
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Abstract: | Carbamate kinase from Streptococcus faecalis is inactivated by butanedione in borate buffer, which implies the presence of an essential arginine at the active site of the enzyme. The inactivation reaction is first order in butanedione] and a replot of the inactivation rate data infers that one arginine is modified. The enzyme is protected against inactivation by ADP, ATP, the metal-nucleotides and carbamyl phosphate but not by carbamate. Amino acid analyses reveal that one of three arginines is modified by butanedione in the absence of protecting agents, and the binding of ADP to the enzyme prevents modification. Thus, analysis of the data suggest that (i) substrate binding to arginine and (ii) protein conformational changes at the active site are responsible for protection of an essential arginine against modification by butanedione. |
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Keywords: | To whom to address correspondence at The Pennsylvania State University J J V is an Established Investigator of the American Heart Association |
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