A sup 1 H NMR probe for mobility in the reactive center loops of serpins: Spin-echo studies of native and modified forms of ovalbumin and. alpha. sub 1 -proteinase inhibitor

Journal Article · Tue Sep 17 00:00:00 EDT 1991 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00101a021· OSTI ID:5701836

Hood, D B; Gettins, P ^[1]

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1. Vanderbilt Univ., Nashville, TN (United States)

It has recently been proposed that the expression of inhibitory activity in serine protease inhibitors (serpins) is a function of the mobility of the extended {alpha}-helical reactive center loop. The authors have employed solution {sup 1}H NMR methods, including the Carr-Purcell-Meiboom-Gill (CPMG) and Hahn spin-echo pulse sequences, to try to identify such regions by virtue of their anticipated longer {Tau}{sub 2} relaxation times in two of the best characterized members of the serpin superfamily, ovalbumin and {alpha}{sub 1}-proteinase inhibitor. The CPMG spectra of native ovalbumin reveal the presence of long-lived resonances form the methyl protons of alanine residues and the CH{sub 3} protons of leucine or valine residues as well as the acetyl and ring methine protons of the carbohydrate moieties. Following reaction of ovalbumin with subtilisin Carlsberg to generate plakalbumin its CPMG spectrum retained almost all of the originally present long-lived resonances. Concurrent with the retention of these mobile resonances in plakalbumin is the appearance of two additional resonances consistent with the formation of new C and N termini. The results suggest that the extended {alpha}-helical loop of serpins is not unusually mobile. These findings and their significance are discussed in terms of the instances of segmental internal motion (i.e., mobility and flexibility) within polypeptide domains demonstrated by NMR spectroscopy, and also with regard to the recently proposed ovalbumin-based model for the mobile reactive center loops of serpins.

• OSTI ID: 5701836
• Journal Information: Biochemistry; (United States), Vol. 30:37; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ENZYME INHIBITORS
NUCLEAR MAGNETIC RESONANCE
SERINE PROTEINASES
BIOCHEMISTRY
ALBUMINS
ENZYME INDUCTION
NMR SPECTRA
POLYPEPTIDES
PROTONS
SPIN ECHO
BARYONS
CHEMISTRY
ELEMENTARY PARTICLES
ENZYMES
FERMIONS
GENE REGULATION
HADRONS
HYDROLASES
MAGNETIC RESONANCE
NUCLEONS
ORGANIC COMPOUNDS
PEPTIDE HYDROLASES
PEPTIDES
PROTEINS
RESONANCE
SPECTRA
550201* - Biochemistry- Tracer Techniques