3aky

STABILITY, ACTIVITY AND STRUCTURE OF ADENYLATE KINASE MUTANTS

spinqualitylabelsall models 3aky, resolution 2.23Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3aky is a 1 chain structure with sequence from Saccharomyces cerevisiae. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: AP5, IMD Activity: Adenylate kinase, with EC number 2.7.4.3 Resources: FirstGlance, OCA, RCSB, PDBsum Function [KAD1_YEAST] Catalyzes the reversible transfer of the terminal phosphate group between ATP and AMP. Plays an important role in cellular energy homeostasis and in adenine nucleotide metabolism. Adenylate kinase activity is critical for regulation of the phosphate utilization and the AMP de novo biosynthesis pathways. 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 Sequence/structure relationships have been explored by site-directed mutagenesis using a structurally known adenylate kinase. In particular the effects of helix capping and nonpolar core expansion on thermodynamic stability have been analyzed. Six point mutations were produced and characterized by SDS/PAGE, native PAGE, isoelectric focussing, electrophoretic titration, enzyme kinetics, and X-ray structure analysis. Heat-denaturation experiments yielded melting temperatures Tm and melting enthalpy changes delta Hm. The heat capacity change delta Cp of the wild-type enzyme was determined by guanidine hydrochloride denaturation in conjunction with Tm and delta Hm. Using the wild-type delta Cp value, Gibbs free energy changes delta G at room temperature were calculated for all mutants. Four mutants were designed for helix capping stabilization, but only one of them showed such an effect. Because of electrostatic interference with the induced-fit motion, one mutant decreased the catalytic activity strongly. Two mutants expanded nonpolar cores causing destabilization. The mutant with the lower stability could be crystallized and subjected to an X-ray analysis at 223-pm resolution which showed the structural changes. The enzyme was stabilized by adding a -Pro-His-His tail to the C-terminal alpha-helix for nickel-chelate chromatography. This addition constitutes a helix cap. Taken together, the results demonstrate that stabilization by helix capping is difficult to achieve because the small positive effect is drowned by adverse mutational disruption. Further addition of atoms to nonpolar cores destabilized the protein, although the involved geometry changes were very small, demonstrating the importance of efficient packing. Stability, activity and structure of adenylate kinase mutants.,Spuergin P, Abele U, Schulz GE Eur J Biochem. 1995 Jul 15;231(2):405-13. PMID:7635152 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Adenylate kinase

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