Biochemistry 1993, 32, 232-240
232
Differential Roles for Three Conserved Histidine Residues within the Large Subunit of Carbamoyl Phosphate Synthetase7 Bryant W. Miles, Shadreck M. Mareya, Laura E. Post, David J. Post, Sun Hee Chang, and Frank M. Raushel’ Department of Chemistry and Center for Macromolecular Design, Texas A&M University, College Station, Texas 77843 Received July 20, 1992; Revised Manuscript Received October 6, 1992
ABSTRACT: Three conserved histidine residues, His-243, His-78 1, and His-788, located within the large subunit of carbamoyl phosphate synthetase from Escherichia coli were identified by sequence identity comparisons. These three histidine residues were individually mutated to asparagine residues. The H243N mutant enzyme was found to be critical for carbamoyl phosphate synthesis as the mutant protein was unable to synthesize carbamoyl phosphate at a significant rate (
