Function of active-site residues of ribulose bisphosphate carboxylase/oxygenase
As one facet of elucidating the mechanism of ribulose-P/sub 2/ carboxylase and of ultimately evaluating the feasibility of altering the carboxylase/oxygenase ratio, active-site characterization has received considerable attention. Chemical modification has revealed five disparate segments of primary structure that appear to constitute the active site. The amino acid sequence of each segment is highly conserved among evolutionarily diverse carboxylases. Site-directed mutagenesis has been used to clarify further the functions of Lys-166, Lys-329, His-291, and Glu-48 of ribulose-P/sub 2/ carboxylase from Rhodospirillum rubrum. These two lysines were selected for examination because of the wealth of data discussed earlier that had implicated their catalytic involvement. His-291 was scrutinized because of the suggestion of its participation, rather than Lys-166, as the proton transfer group that enolizes ribulose-P/sub 2/. The reasons for inspecting Glu-48 were circumstantial. Within the homologous region flanked by His-44 and Cys-58, targets of an affinity label, Glu-48 is the only acid/base group and hence a logical candidate for functionality. Furthermore, crystallographic and chemical cross-linking studies had placed this NH/sub 2/-terminal region near the active site. 33 refs.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6432826
- Report Number(s):
- CONF-8706127-1; ON: DE87011124
- Resource Relation:
- Conference: Plant molecular biology, Copenhagen, Denmark, 10 Jun 1987
- Country of Publication:
- United States
- Language:
- English
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Ribulose bisphosphate carboxylase/oxygenase: Active-site characterization and function of critical residues
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59 BASIC BIOLOGICAL SCIENCES
RIBULOSE DIPHOSPHATE CARBOXYLASE
BIOCHEMICAL REACTION KINETICS
GENE MUTATIONS
STRUCTURE-ACTIVITY RELATIONSHIPS
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CARBOXY-LYASES
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