Value of General Acid-Base Catalysis to Ribonuclease A
نویسندگان
چکیده
منابع مشابه
Value of general Acid-base catalysis to ribonuclease a.
Bovine pancreatic ribonuclease A (RNase A; EC 3.1.27.5) has been one of the most studied of all enzymes.’ RNase A efficiently catalyzes the cleavage of RNA.2 Early X-ray diffraction analyses revealed that the active site of RNase A contains two histidine residues, histidine 12 (H12) and histidine 119 (H1 19).3 The results of chemical modification4 and pHrate’ studies are consistent with an enzy...
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A general acid-base catalytic mechanism for ribonuclease A and other ribonucleases was previously widely accepted. However, an alternative to this mechanism was recently reintroduced in which attack by the 2‘ hydroxyl group is facilitated by protonation of a nonbridging phosphoryl oxygen atom, instead of the leaving group oxygen atom, to give a triester-like mechanism of catalysis. Literature v...
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Bovine pancreatic ribonuclease A (RNase A) catalyzes the cleavage of the P-O(5') bond in RNA. Although this enzyme has been the object of much landmark work in bioorganic chemistry, the nature of its rate-limiting transition state and its catalytic rate enhancement had been unknown. Here, the value of k(cat)/K(m) for the cleavage of UpA by wild-type RNase A was found to be inversely related to ...
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The reaction of phenyl acetate with pyrazole is catalyzed by general bases and by bifunctional general acids. The Br~lnsted plot for general base catalysis shows downward curvature. It is consistent with either a Hammond effect on proton transfer, as described by a positive coefficient p x = a/3/-apKAH, or separate lines with p = 0.65 for cacodylate and substituted acetate monoanions and /3 = 0...
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Acid-base catalyzed glycosyl donor and then glycosyl acceptor activation with phenylboron difluoride or diphenylboron fluoride permits hydrogen bond mediated intramolecular S(N)2-type glycosidation in generally high anomeric selectivity.
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ژورنال
عنوان ژورنال: Journal of the American Chemical Society
سال: 1994
ISSN: 0002-7863,1520-5126
DOI: 10.1021/ja00091a060