1zr0
Crystal Structure of Kunitz Domain 1 of Tissue Factor Pathway Inhibitor-2 with Bovine Trypsin
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OverviewOverview
Kunitz domain 1 (KD1) of tissue factor pathway inhibitor-2 inhibits, trypsin, plasmin, and factor VIIa (FVIIa)/tissue factor with Ki values of, 13, 3, and 1640 nM, respectively. To investigate the molecular specificity, of KD1, crystals of the complex of KD1 with bovine beta-trypsin were, obtained that diffracted to 1.8 A. The P1 residue Arg-15 (bovine, pancreatic trypsin inhibitor numbering) in KD1 interacts with Asp-189, (chymotrypsin numbering) and with the carbonyl oxygens of Gly-219 and, Ogamma of Ser-190. Leu-17, Leu-18, Leu-19, and Leu-34 in KD1 make van der, Waals contacts with Tyr-39, Phe-41, and Tyr-151 in trypsin, forming a, hydrophobic interface. Molecular modeling indicates that this, complementary hydrophobic patch is composed of Phe-37, Met-39, and Phe-41, in plasmin, whereas in FVIIa/tissue factor, it is essentially absent., Arg-20, Tyr-46, and Glu-39 in KD1 interact with trypsin through ordered, water molecules. In contrast, insertions in the 60-loop in plasmin and, FVIIa allow Arg-20 of KD1 to directly interact with Glu-60 in plasmin and, Asp-60 in FVIIa. Moreover, Tyr-46 in KD1 electrostatically interacts with, Lys-60A and Arg-60D in plasmin and Lys-60A in FVIIa. Glu-39 in KD1, interacts directly with Arg-175 of the basic patch in plasmin, whereas in, FVIIa, such interactions are not possible. Thus, the specificity of KD1, for plasmin is attributable to hydrophobic and direct electrostatic, interactions. For trypsin, hydrophobic interactions are intact, and, electrostatic interactions are weak, whereas for FVIIa, hydrophobic, interactions are missing, and electrostatic interactions are partially, intact. These findings provide insight into the protease selectivity of, KD1.
About this StructureAbout this Structure
1ZR0 is a Protein complex structure of sequences from Bos taurus and Homo sapiens with CA as ligand. Active as Trypsin, with EC number 3.4.21.4 Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of Kunitz domain 1 (KD1) of tissue factor pathway inhibitor-2 in complex with trypsin. Implications for KD1 specificity of inhibition., Schmidt AE, Chand HS, Cascio D, Kisiel W, Bajaj SP, J Biol Chem. 2005 Jul 29;280(30):27832-8. Epub 2005 Jun 2. PMID:15932872
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