Abdur Rehman - Academia.edu (original) (raw)
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Current Microbiology, 1997
Cysteine 195 in isocitrate lyase from Escherichia coli has been replaced by directed mutagenesis.... more Cysteine 195 in isocitrate lyase from Escherichia coli has been replaced by directed mutagenesis. Substitution by Ser yields enzyme with a k cat that is 0.03% that of wild type, and substitution by Ala, Gly, Thr, or Val yields completely inactive enzyme. The present results are consistent with a functional role of Cys 195.
Current Microbiology, 1997
With site-directed mutagenesis, Ser319 and Ser321 in conserved stretch 3 of tetrameric isocitrate... more With site-directed mutagenesis, Ser319 and Ser321 in conserved stretch 3 of tetrameric isocitrate lyase from Escherichia coli were each substituted with alanine, cysteine, asparagine, or threonine in addition to simultaneous alanine/alanine substitutions. Besides their absolute conservation in all aligned isocitrate lyase sequences, the location of these serine residues, which flank a completely conserved proline, had been suggested in the active site in previous research by studies of photoinactivation of the enzyme by vanadate [Ko et al. (1992) J Biol Chem 267:91]. All substitutions for Ser321 and 319 except by threonine appreciably reduced the k cat of E. coli isocitrate lyase relative to that for wild-type (100) as follows:
Current Microbiology, 1997
Cysteine 195 in isocitrate lyase from Escherichia coli has been replaced by directed mutagenesis.... more Cysteine 195 in isocitrate lyase from Escherichia coli has been replaced by directed mutagenesis. Substitution by Ser yields enzyme with a k cat that is 0.03% that of wild type, and substitution by Ala, Gly, Thr, or Val yields completely inactive enzyme. The present results are consistent with a functional role of Cys 195.
Current Microbiology, 1997
With site-directed mutagenesis, Ser319 and Ser321 in conserved stretch 3 of tetrameric isocitrate... more With site-directed mutagenesis, Ser319 and Ser321 in conserved stretch 3 of tetrameric isocitrate lyase from Escherichia coli were each substituted with alanine, cysteine, asparagine, or threonine in addition to simultaneous alanine/alanine substitutions. Besides their absolute conservation in all aligned isocitrate lyase sequences, the location of these serine residues, which flank a completely conserved proline, had been suggested in the active site in previous research by studies of photoinactivation of the enzyme by vanadate [Ko et al. (1992) J Biol Chem 267:91]. All substitutions for Ser321 and 319 except by threonine appreciably reduced the k cat of E. coli isocitrate lyase relative to that for wild-type (100) as follows: