1y3c
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| , resolution 1.69Å | |||||||
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| Ligands: | , , and | ||||||
| Gene: | apr (Bacillus amyloliquefaciens) | ||||||
| Activity: | Subtilisin, with EC number 3.4.21.62 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Crystal structure of the complex of subtilisin BPN' with chymotrypsin inhibitor 2 R62A mutant
OverviewOverview
A series of mutants of chymotrypsin inhibitor 2 (CI2), at residues involved in intramolecular interactions that shape and constrain the binding loop, were studied to determine their relative importance for inhibition of the serine protease subtilisin BPN', and for resistance of the inhibitor to proteolysis. These functional properties were investigated in tandem with the crystal structures of the mutant inhibitor-enzyme complexes. A dense hydrogen bonding network that supports the binding loop in the vicinity of the scissile bond was found to be important both for enzyme affinity and for stability to proteolysis. Structural analysis, in combination with biochemical measurements, allows differentiation of the structural components most important for resistance to proteolysis and/or binding. The most critical participating residues in the network were found to be Thr-58, Glu-60, Arg-65, and Gly-83. Glu-60 is more important for resistance to proteolysis than for binding, while Arg-65 and two other Arg residues play a greater role in binding than in resistance to proteolysis. Structural comparisons reveal a wide variety of subtle conformational changes in response to mutation, with built-in robustness in the hydrogen bond network, such that loss of one contact is compensated by other new contacts.
About this StructureAbout this Structure
1Y3C is a Protein complex structure of sequences from Bacillus amyloliquefaciens and Hordeum vulgare. Full crystallographic information is available from OCA.
ReferenceReference
Role of the intramolecular hydrogen bond network in the inhibitory power of chymotrypsin inhibitor 2., Radisky ES, Lu CJ, Kwan G, Koshland DE Jr, Biochemistry. 2005 May 10;44(18):6823-30. PMID:15865427
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