Glu 46 of ribonuclease T1 is an essential residue for the recognition of guanine base.
The Glu 46 of ribonuclease T1, which is assumed to interact with Nl of the guanine residue in RNA by a hydrogen bond from the result of X-ray analysis, was changed to alanine by site-directed mutagenesis and its function examined. The nucleolytic activity of the Ala 46 mutant enzyme against pGpC decreased to 0.4% of that of the wild-type enzyme, on the other hand its activity against pApC increased. This result suggests that the Glu 46 is essential for the recognition of the guanine base but that it also interferes with the recognition of the adenine base.
D000409:Alanine; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D004591:Electrophoresis, Polyacrylamide Gel; D004722:Endoribonucleases / Q000378:metabolism*; D005973:Glutamine; D006147:Guanine / Q000378:metabolism*; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D009154:Mutation; D009841:Oligonucleotides / Q000378:metabolism; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D006163:Ribonuclease T1 / Q000235:genetics / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
D009841:Oligonucleotides; D011993:Recombinant Fusion Proteins; D005973:Glutamine; D006147:Guanine; D004722:Endoribonucleases; D006163:Ribonuclease T1; D000409:Alanine