3tgk | pdb_00003tgk

TRYPSINOGEN MUTANT D194N AND DELETION OF ILE 16-VAL 17 COMPLEXED WITH BOVINE PANCREATIC TRYPSIN INHIBITOR (BPTI)

spinqualitylabelsall models 3tgk, resolution 1.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3tgk is a 2 chain structure with sequence from Bos taurus and Rattus norvegicus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.7Å Ligands: CA, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function TRY2_RAT 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 contribution of induced fit to enzyme specificity has been much debated, although with little experimental data. Here we probe the effect of induced fit on enzyme specificity using the trypsin(ogen) system. BPTI is known to induce trypsinogen to assume a trypsinlike conformation. Correlations are observed between BPTI affinity and the values of k(cat)/K(m) for the hydrolysis of two substrates by eight trypsin(ogen) variants. The slope of both correlations is -1.8. The crystal structures of the BPTI complexes of four variant trypsinogens were also solved. Three of these enzymes, K15A, DeltaI16V17/D194N, and DeltaI16V17/Q156K trypsinogen, are 10- to 100-fold more active than trypsinogen. The fourth variant, DeltaI16V17 trypsinogen, is the lone outlier in the correlations; its activity is lower than expected based on its affinity for BPTI. The S1 site and oxyanion hole, formed by segments 184A-194 and 216-223, are trypsinlike in all of the enzymes. These structural and kinetic data confirm that BPTI induces an active conformation in the trypsin(ogen) variants. Thus, changes in BPTI affinity monitor changes in the energetic cost of inducing a trypsinlike conformation. Although the S1 site and oxyanion hole are similar in all four variants, the N-terminal and autolysis loop (residues 142-152) segments have different interactions for each variant. These results indicate that zymogen activity is controlled by a simple conformational equilibrium between active and inactive conformations, and that the autolysis loop and N-terminal segments control this equilibrium. Together, these data illustrate that induced fit does not generally contribute to enzyme specificity. The energetic cost of induced fit catalysis: Crystal structures of trypsinogen mutants with enhanced activity and inhibitor affinity.,Pasternak A, White A, Jeffery CJ, Medina N, Cahoon M, Ringe D, Hedstrom L Protein Sci. 2001 Jul;10(7):1331-42. PMID:11420435 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also BPTI 3D structures Trypsin 3D structures

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