ISSN:
1573-4943
Keywords:
activated protein C
;
cation binding sites
;
Tl+-protein complexes
;
Tl+-NMR
;
distance calculations on proteins
;
paramagnetic effects
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The paramagnetic effect of a spin-labeled sulfonyl fluoride, 4-(2,2,5,5-tetramethylpyrrolidine-1-oxyl)-p-fluorosulfonylbenzamide (p-V), when bound to the active site serine residue of the proteases, bovine plasma-activated protein C (APC) and des(1–41)-light-chain-activated protein C (GDAPC), on the longitudinal relaxation rate (T1) of Tl+ bound to these same proteins has been examined by 205Tl+-NMR spectroscopy. The substantial shortening by bound p-V of the T1 for Tl+ has been employed to estimate the distances between Tl+ and the unpaired electron on each protein surface. Assuming that a single cation-binding site exists on each enzyme, electron-nuclear distances of 3.4–3.9 Å have been calculated for each protein. This suggests that the removal of 41 amino acid residues and, concomitantly, all γ-carboxyglutamic acid, from the amino-terminal of the light chain of APC, does not significantly affect the protein topography in the region of the molecule probed by this technique.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00276735
Permalink
