Role of electrostatic repulsion on colloidal stability of Bacillus halmapalus alpha-amylase.
Biochim Biophys Acta
; 1794(7): 1058-65, 2009 Jul.
Article
em En
| MEDLINE
| ID: mdl-19281873
ABSTRACT
The colloidal stability of charged particles in suspension is often controlled by electrostatic repulsion, which can be rationalized in a semi-quantitative way by the DLVO theory. In the current study, we investigate this approach towards understanding irreversible protein aggregation, using Bacillus halmapalus alpha-amylase (BHA) as a model protein. Repulsive forces between partly unfolded monomers were shown to strongly affect aggregation. Adding salt, increasing valence of counter ions or decreasing pH in the direction of pI resulted in a shift in the rate-limiting step from association to unfolding as evidenced by a change in aggregation kinetics from second to first-order in protein concentration. Charge screening effects by salts resulted in increased average size of protein aggregates but only moderately affected the secondary structure of protein within the aggregates. Salt and pH effects could be explained within the DLVO framework, indicating that partially unfolded BHA monomers can be modelled realistically as colloids with a random charge distribution.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Bacillus
/
Coloides
/
Alfa-Amilases
/
Eletricidade Estática
Idioma:
En
Revista:
Biochim Biophys Acta
Ano de publicação:
2009
Tipo de documento:
Article
País de afiliação:
Dinamarca