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Dissertation/Thesis Abstract

Crystallography at ultrahigh and infralow resolution: Studies of carbonic anhydrase and ribonuclease P
by Jude, Kevin, Ph.D., University of Pennsylvania, 2007, 139; 3261016
Abstract (Summary)

Crystal structures of carbonic anhydrase (CA) isozymes I and II in complex with Cu2+-containing "two-prong" inhibitors and with derivatives of p-aminobenzenesulfonamide (pAEBS) and of p-carboxylbenzenesulfonamide (pCEBS) are reported here. These structures shed light on determinants of isozyme-specific inhibition of carbonic anhydrases as mediated by both specific, enthalpy-driven, and nonspecific, entropy-driven, interactions.

Additionally, the structure of F65A/Y131C murine CAV, covalently modified at cysteine residues with 4-chloromethylimidazole, is reported. The introduction of a methylimidazole (MI) group at residue C131 in the active site results in up to a 3-fold rate enhancement of CO2 hydration by the enzyme versus wild-type activity. This structure demonstrates that C131-MI acts as a proton shuttle to facilitate deprotonation of a zinc-bound water molecule to regenerate the nucleophilic zinc-bound hydroxide ion. A network of three hydrogen-bonded water molecules, across which proton transfer likely proceeds, bridges the zinc-bound water molecule and the C131-MI imidazole group. Comparison with other carbonic anhydrase crystal structures allows common features of catalytic proton shuttles to be outlined.

Furthermore, crystallization of the ribozyme ribonuclease P from Bacillus subtilis is reported here. Crystallization of the RNA subunit and of a complex containing both the RNA subunit and the product tRNA is reported, as well as initial progress in phasing the structure of the ribonuclease P holoenzyme, comprising a 130 kD RNA subunit and a 14 kD protein subunit. This represents the first report of crystallization of a ribonuclease P-product complex.

Indexing (document details)
Advisor: Christianson, David W.
School: University of Pennsylvania
School Location: United States -- Pennsylvania
Source: DAI-B 68/04, Dissertation Abstracts International
Subjects: Biochemistry
Keywords: Carbonic anhydrase, Ribonuclease P, Ribozymes
Publication Number: 3261016
ISBN: 978-1-109-98601-3
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