1q5p

S156E/S166D variant of Bacillus lentus subtilisin

spinqualitylabelsall models 1q5p, resolution 1.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1q5p is a 1 chain structure with sequence from Bacillus lentus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CA, SO4 NonStd Res: SEB Activity: Subtilisin, with EC number 3.4.21.62 Resources: FirstGlance, OCA, RCSB, PDBsum Function [SUBS_BACLE] Subtilisin is an extracellular alkaline serine protease, it catalyzes the hydrolysis of proteins and peptide amides. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The properties of the transition state for serine protease-catalyzed hydrolysis of an amide bond were determined for a series of subtilisin variants from Bacillus lentus. There is no significant change in the structure of the enzyme upon introduction of charged mutations S156E/S166D, suggesting that changes in catalytic activity reflect global properties of the enzyme. The effect of charged mutations on the pK(a) of the active site histidine-64 N(epsilon)(2)-H was correlated with changes in the second-order rate constant k(cat)/K(m) for hydrolysis of tetrapeptide anilides at low ionic strength with a Bronsted slope alpha = 1.1. The solvent isotope effect (D)2(O)(k(cat)/K(m))(1) = 1.4 +/- 0.2. These results are consistent with a rate-limiting breakdown of the tetrahedral intermediate in the acylation step with hydrogen bond stabilization of the departing amine leaving group. There is an increase in the ratio of hydrolysis of succinyl-Ala-Ala-Pro-Phe-anilides for p-nitroaniline versus aniline leaving groups with variants with more basic active site histidines that can be described by the interaction coefficient p(xy) = delta beta(lg)/delta pK(a) (H64) = 0.15. This is attributed to increased hydrogen bonding of the active site imidazolium N-H to the more basic amine leaving group as well as electrostatic destabilization of the transition state. A qualitative characterization of the transition state is presented in terms of a reaction coordinate diagram that is defined by the structure-reactivity parameters. Do enzymes change the nature of transition states? Mapping the transition state for general acid-base catalysis of a serine protease.,Bott RR, Chan G, Domingo B, Ganshaw G, Hsia CY, Knapp M, Murray CJ Biochemistry. 2003 Sep 16;42(36):10545-53. PMID:12962477 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Subtilisin

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