ELECTROSTATIC INTERACTIONS IN THE ACID DENATURATION OF ALPHA-LACTALBUMIN DETERMINED BY NMR

Authors
Citation
S. Kim et J. Baum, ELECTROSTATIC INTERACTIONS IN THE ACID DENATURATION OF ALPHA-LACTALBUMIN DETERMINED BY NMR, Protein science, 7(9), 1998, pp. 1930-1938
Citations number
64
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biology
Journal title
ISSN journal
0961-8368
Volume
7
Issue
9
Year of publication
1998
Pages
1930 - 1938
Database
ISI
SICI code
0961-8368(1998)7:9<1930:EIITAD>2.0.ZU;2-R
Abstract
alpha-Lactalbumin (alpha-LA) undergoes a pH-dependent unfolding from t he native state to a partially unfolded state (the molten globule stat e). To understand the role of electrostatic interactions in protein de naturation, NMR and CD pH titration experiments are performed on guine a pig alpha-LA. Variation of pH over the range of 7.0 to 2.0 simultane ously leads to the acid denaturation of the protein and the titration of individual ionizable soups. The pH titrations are interpreted in th e context of these coupled events, and indicate that acid denaturation in alpha-LA is a cooperative event that is triggered by the protonati on of two ionizable residues. Our NMR results suggest that the critica l electrostatic interactions that contribute to the denaturation of al pha-LA are concentrated in the calcium binding region of the protein.