Protein encapsulation by humic substances.
Environ Sci Technol
; 45(14): 6003-10, 2011 Jul 15.
Article
em En
| MEDLINE
| ID: mdl-21678916
ABSTRACT
Protein encapsulation by natural organic matter is hypothesized to preserve the activity of proteins in terrestrial and aquatic environments. Direct molecular-level evidence for encapsulation of net positively charged proteins lysozyme, trypsin, and ribonuclease A by a diverse set of humic substances (HS) in nanostructured films was collected using a combination of optical waveguide lightmode spectroscopy and quartz crystal microbalance measurements. The results suggest that protein-HS electrostatic attraction drives encapsulation of positively charged lysozyme by a soil humic acid at pH 5 to 8 and by six additional humic and fulvic acids from terrestrial and mixed terrestrial aquatic sources at pH 5 and 6. Encapsulation of trypsin and ribonuclease A, which had negatively charged surface patches under the studied conditions, suggested that localized protein-HS electrostatic repulsion is overcompensated by attractive forces, likely including contributions from the hydrophobic effect. Evidence is provided showing that encapsulation of lysozyme at pH 8 and of ribonuclease A at pH 5 and 6 involved partial disassembly of HA supramolecular associations. This work advances a molecular-level picture of protein encapsulation by HS and presents a novel approach to study the effects of encapsulation on protein enzymatic activity and susceptibility to abiotic and biotic transformations.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas
/
Modelos Moleculares
/
Nanoestruturas
/
Substâncias Húmicas
Idioma:
En
Revista:
Environ Sci Technol
Ano de publicação:
2011
Tipo de documento:
Article
País de afiliação:
Suíça