June M. Messmore

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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(More)
Bovine pancreatic ribonuclease A (RNase A) catalyzes the cleavage of P-Os bonds in RNA. Structural analyses had suggested that the active-site lysine residue (Lys41) may interact preferentially with the transition state for covalent bond cleavage, thus facilitating catalysis. Here, site-directed mutagenesis and semisynthesis were combined to probe the role(More)
Pentavalent organo-vanadates have been put forth as transition state analogues for a variety of phosphoryl transfer reactions. In particular, uridine 2',3'-cyclic vanadate (U>v) has been proposed to resemble the transition state during catalysis by ribonuclease A (RNase A). Here, this hypothesis is tested. Lys41 of RNase A is known to donate a hydrogen bond(More)
The facile modulation of biological processes is an important goal of biological chemists. Here, a general strategy is presented for controlling the catalytic activity of an enzyme. This strategy is demonstrated with ribonuclease A (RNase A), which catalyzes the cleavage of RNA. The side-chain amino group of Lys41 donates a hydrogen bond to a nonbridging(More)
Pentavalent organo-vanadates have been used extensively to mimic the transition state of phosphoryl group transfer reactions. Here, decavanadate (V(10)O(28)6-) is shown to be an inhibitor of catalysis by bovine pancreatic ribonuclease A (RNase A). Isothermal titration calorimetry shows that the Kd for the RNase A decavanadate complex is 1.4 microM. This(More)
June M. Messmore Under the supervision of Professor Ronald T. Raines at the University of Wisconsin-Madison 1 Structural analyses had suggested that the active-site lysine residue of RNase A (Lys41) may interact preferentially with the transition state for covalent bond cleavage, thus facilitating catalysis. Site-directed mutagenesis and chemical(More)
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