1uto

File:1uto.gif

spinqualitylabelsall models 1uto, resolution 1.15Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

TRYPSIN SPECIFICITY AS ELUCIDATED BY LIE CALCULATIONS, X-RAY STRUCTURES AND ASSOCIATION CONSTANT MEASUREMENTS

OverviewOverview

The variation in inhibitor specificity for five different amine inhibitors, bound to CST, BT, and the cold-adapted AST has been studied by use of, association constant measurements, structural analysis of high-resolution, crystal structures, and the LIE method. Experimental data show that AST, binds the 1BZA and 2BEA inhibitors 0.8 and 0.5 kcal/mole more strongly, than BT. However, structural interactions and orientations of the, inhibitors within the S1 site have been found to be virtually identical in, the three enzymes studied. For example, the four water molecules in the, inhibitor-free structures of AST and BT are channeled into similar, positions in the S1 site, and the nitrogen atom(s) of the inhibitors are, found in two cationic binding sites denoted Position1 and Position2. The, hydrophobic binding contributions for all five inhibitors, estimated by, the LIE calculations, are also in the same order (-2.1 +/- 0.2 kcal/mole), for all three enzymes. Our hypothesis is therefore that the observed, variation in inhibitor binding arises from different electrostatic, interactions originating from residues outside the S1 site. This is well, illustrated by AST, in which Asp 150 and Glu 221B, despite some distance, from the S1 binding site, lower the electrostatic potential of the S1 site, and thus enhance substrate binding. Because the trends in the, experimentally determined binding energies were reproduced by the LIE, calculations after adding the contribution from long-range interactions, we find this method very suitable for rational studies of, protein-substrate interactions.

About this StructureAbout this Structure

1UTO is a Single protein structure of sequence from Bos taurus with CA, PEA and GOL as ligands. Active as Trypsin, with EC number 3.4.21.4 Known structural/functional Site: . Full crystallographic information is available from OCA.

ReferenceReference

Trypsin specificity as elucidated by LIE calculations, X-ray structures, and association constant measurements., Leiros HK, Brandsdal BO, Andersen OA, Os V, Leiros I, Helland R, Otlewski J, Willassen NP, Smalas AO, Protein Sci. 2004 Apr;13(4):1056-70. PMID:15044735

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