Two histidine residues are essential for ribonuclease T/sub 1/ activity as is the case for ribonuclease
Journal Article
·
· Biochemistry; (United States)
OSTI ID:5381682
Ribonuclease T/sub 1/ (RNase T/sub 1/, EC 3.1.27.3) is a guanosine-specific ribonuclease that cleaves the 3',5'-phosphodiester linkage of single-stranded RNA. It is assumed that the reaction is generated by concerted acid-base catalysis between residues Glu-58 and His-92 or His-40. From the results of chemical modification and NMR studies, it appeared that the residue Glu-58 was indispensable for nucleolytic activity. However, the authors have recently demonstrated that Glu-58 is an important but not an essential residue for catalytic activity, using the methods of genetic engineering to change Glu-58 to Gln-58 etc. In the present paper, the authors report that mutants of RNase T/sub 1/ with residue Ala-40 or Ala-92 have almost no activity, while mutants that contain Ala-58 retain considerable activity. These results show that the two histidine residues, His-40 and His-92, but not Glu-58, are indispensable for the catalytic activity of the enzyme. They propose a revised reaction mechanism in which two histidine residues play a major role, as they do in the case of RNase A.
- Research Organization:
- Osaka Univ. (Japan)
- OSTI ID:
- 5381682
- Journal Information:
- Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 26:26; ISSN BICHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
AUTORADIOGRAPHY
AZOLES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
CARBOXYLIC ACIDS
CATALYSIS
COMPUTER GRAPHICS
DAYS LIVING RADIOISOTOPES
DNA
DNA SEQUENCING
ELECTROPHORESIS
ENZYME ACTIVITY
ENZYMES
ESTERASES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HISTIDINE
HYDROLASES
IMIDAZOLES
ISOTOPES
KINETICS
LIGHT NUCLEI
NUCLEI
NUCLEIC ACIDS
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOSPHODIESTERASES
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
RADIOISOTOPES
REACTION KINETICS
RNA
RNA-ASE
STRUCTURAL CHEMICAL ANALYSIS
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
AUTORADIOGRAPHY
AZOLES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
CARBOXYLIC ACIDS
CATALYSIS
COMPUTER GRAPHICS
DAYS LIVING RADIOISOTOPES
DNA
DNA SEQUENCING
ELECTROPHORESIS
ENZYME ACTIVITY
ENZYMES
ESTERASES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HISTIDINE
HYDROLASES
IMIDAZOLES
ISOTOPES
KINETICS
LIGHT NUCLEI
NUCLEI
NUCLEIC ACIDS
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOSPHODIESTERASES
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
RADIOISOTOPES
REACTION KINETICS
RNA
RNA-ASE
STRUCTURAL CHEMICAL ANALYSIS