1hym
From Proteopedia
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HYDROLYZED TRYPSIN INHIBITOR (CMTI-V, MINIMIZED AVERAGE NMR STRUCTURE)
Overview
Reactive-site (Lys44-Asp45 peptide bond) hydrolyzed Cucurbita maxima, trypsin inhibitor-V (CMTI-V*) was prepared and characterized: In, comparison to the intact form, CMTI-V* exhibited markedly reduced, inhibitory properties and binding affinities toward trypsin and human, blood coagulation factor XIIa. The equilibrium constant of, trypsin-catalyzed hydrolysis, Khyd, defined as [CMTI-V*]/[CMTI-V], was, measured to be approximately 9.4 at 25 degrees C (delta G degrees = -1.3, kcal.mol-1). From the temperature dependence of delta G degrees, the, following thermodynamic parameters were estimated: delta H degrees = 1.6, kcal.mol-1 and delta S degrees = 9.8 eu. In order to understand the, functional and thermodynamic differences between the two forms, the, three-dimensional solution structure of CMTI-V* was determined by a, combined approach of NMR, distance geometry, and simulated annealing, methods. Thus, following sequence-specific and stereospecific resonance, assignments, including those of beta-, gamma-, delta-, and, epsilon-hydrogens and valine methyl hydrogens, 809 interhydrogen distances, and 123 dihedral angle constraints were determined, resulting in the, computation and energy-minimization of 20 structures for CMTI-V*. The, average root mean squared deviation in position for equivalent atoms, between the 20 individual structures and the mean structure obtained by, averaging their coordinates is 0.67 +/- 0.15 A for the main chain atoms, and 1.19 +/- 0.23 A for all the non-hydrogen atoms of residues 5-40 and, residues 48-67.(ABSTRACT TRUNCATED AT 250 WORDS)
About this Structure
1HYM is a Protein complex structure of sequences from Cucurbita maxima with ACE as ligand. Full crystallographic information is available from OCA.
Reference
Reactive-site hydrolyzed Cucurbita maxima trypsin inhibitor-V: function, thermodynamic stability, and NMR solution structure., Cai M, Gong Y, Prakash O, Krishnamoorthi R, Biochemistry. 1995 Sep 26;34(38):12087-94. PMID:7547948
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