13C-NMR of Clostridium pasteurianum ferredoxin after reductive methylation of the amines using [13C]formaldehyde.
Biochim Biophys Acta
; 1038(2): 146-51, 1990 Apr 19.
Article
em En
| MEDLINE
| ID: mdl-2331479
ABSTRACT
Clostridium pasteurianum 2(4Fe-4S) ferredoxin has been reductively methylated using [13C]formaldehyde and sodium cyanoborohydride. Lys3 and the N-terminal alanine, the only amines in the protein, are both dimethylated by this procedure. 13C-NMR titration of the apo, oxidized and reduced modified ferrodoxin indicate that the lysine pK is slightly over 10 in all three forms of the protein. In contrast, the N-terminal alanine shifts from a pK of 7.7 in the apoprotein to greater than 9 in both the oxidized and reduced modified ferredoxin. The unexpectedly high pK observed for the N-terminus is consistent with the presence of an ion pair in both the oxidized and reduced native forms of the protein. The methylated ferrodoxin is considerably less stable than the native protein, indicating an important role for the amines in protein stability.
Buscar no Google
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Clostridium
/
Ferredoxinas
Idioma:
En
Ano de publicação:
1990
Tipo de documento:
Article