Pressure effect on the conformational fluctuation of apomyoglobin in the native state

Citation
N. Tanaka et al., Pressure effect on the conformational fluctuation of apomyoglobin in the native state, BIOCHEM, 39(39), 2000, pp. 12063-12068
Citations number
42
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biochemistry & Biophysics
Journal title
BIOCHEMISTRY
ISSN journal
0006-2960 → ACNP
Volume
39
Issue
39
Year of publication
2000
Pages
12063 - 12068
Database
ISI
SICI code
0006-2960(20001003)39:39<12063:PEOTCF>2.0.ZU;2-Y
Abstract
We have investigated the effect of pressure on fluctuations of the native s tate of sperm whale apomyoglobin (apoMb) by H/D exchange, fluorescence, and limited proteolysis. The results from intrinsic fluorescence showed that a large fraction of apoMb molecules is in the native conformation in the pre ssure range from 0.1 to 150 MPa at 293 K and pH 6.0. The H/D exchange of pr otons of the individual backbone amino acids in this pressure range was mon itored by NMR, The rate of H/D exchange was enhanced at high pressure, with the protection factors for some residues decreasing by factors of more tha n 100 compared to the values at 0.1 MPa. The amplitude of the decrease of t he protection factor varied among the individual amino acids on the same se condary structure unit. This result suggests that H/D exchange in apoMb is explained best by the penetration model, in which solvent penetrates into t he protein matrix via small motions. The result from limited proteolysis un der high pressure showed that a pressure increase does not induce local unf olding of the secondary structure units of apoMb. Conformational fluctuatio ns much smaller than local unfolding evidently provide pathways for water t o diffuse into the protein interior, and are enhanced by an increase of pre ssure.