1HYM

HYDROLYZED TRYPSIN INHIBITOR (CMTI-V, MINIMIZED AVERAGE NMR STRUCTURE)

Summary for 1HYM

• Entry DOI: 10.2210/pdb1hym/pdb
• Descriptor: HYDROLYZED CUCURBITA MAXIMA TRYPSIN INHIBITOR V (2 entities in total)
• Functional Keywords: hydrolase (serine proteinase)
• Biological source: Cucurbita maxima (winter squash); More
• Total number of polymer chains: 2
• Total formula weight: 7418.65

Authors

Cai, M.,Gong, Y.,Prakash, O.,Krishnamoorthi, R. (deposition date: 1995-06-12, release date: 1995-09-15, Last modification date: 2024-11-06)

Primary citation

Cai, M.,Gong, Y.,Prakash, O.,Krishnamoorthi, R.
Reactive-site hydrolyzed Cucurbita maxima trypsin inhibitor-V: function, thermodynamic stability, and NMR solution structure.
Biochemistry, 34:12087-12094, 1995

PubMed Abstract: 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)

PubMed: 7547948
DOI: 10.1021/bi00038a001

Experimental method

SOLUTION NMR