Two-dimensional NMR studies of squash family inhibitors. Sequence-specific proton assignments and secondary structure of reactive-site hydrolyzed Cucurbita maxima trypsin inhibitor III

Journal Article · Tue Jan 28 04:00:00 EST 1992 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00118a036· OSTI ID:5687918

Krisnamoorthi, R; Gong, Yuxi; Lin, Chanlan Sun ^[1]; VanderVelde, D ^[2]

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1. Kansas State Univ., Manhattan (United States)
2. Univ. of Kansas, Lawrence (United States)

The solution structure of reactive-site hydrolyzed Cucurbita maxima trypsin inhibitor III (CMTI-III*) was investigated by two-dimensional proton nuclear magnetic resonance (2D NMR) spectroscopy. CMTI-III*, prepared by reacting CMTI-III with trypsin which cleaved the Arg5-Ile6 peptide bond, had the two fragments held together by a disulfide linkage. Sequence-specific {sup 1}H NMR resonance assignments were made for all the 29 amino acid residues of the protein. The secondary structure of CMTI-III*, as deduced from NOESY cross peaks and identification of slowly exchanging hydrogens, contains two turns, a 3{sub 10}-helix, and a triple-stranded {beta}-sheet. Sequential proton assignments were also made for the virgin inhibitor, CMTI-III, at pH 4.71, 30C. Comparison of backbone hydrogen chemical shifts of CMTI-III and CMTI-III* revealed significant changes for residues located far away from the reactive-site region as well as for those located near it, indicating tertiary structural changes that are transmitted through most of the 29 residues of the inhibitor protein. These chemical shift changes were relatively small compared to changes that occurred upon hydrolysis of the reactive-site peptide bond between Arg 5 and Ile6 in CMTI-III.

• OSTI ID: 5687918
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 31:3; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AQUEOUS SOLUTIONS
BARYONS
BIOCHEMICAL REACTION KINETICS
CHEMICAL SHIFT
DISPERSIONS
ELEMENTARY PARTICLES
ENZYME INHIBITORS
ENZYMES
FERMIONS
HADRONS
HEAVY WATER
HYDROGEN COMPOUNDS
HYDROLASES
KINETICS
MAGNETIC RESONANCE
MIXTURES
NUCLEAR MAGNETIC RESONANCE
NUCLEONS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PEPTIDE HYDROLASES
PROTEINS
PROTONS
REACTION KINETICS
RESONANCE
SERINE PROTEINASES
SOLUTIONS
TRYPSIN
WATER