Isocyanide binding kinetics to monomeric hemoproteins. A study on the ligand partition between solvent and heme pocket.
Biophys J
; 51(3): 357-62, 1987 Mar.
Article
en En
| MEDLINE
| ID: mdl-3567310
The kinetics of methyl-, ethyl-, iso-propyl-, and ter-butyl-isocyanide binding to Aplysia limacina myoglobin (distal His----Lys) and the isolated beta chains from hemoglobin Zurich (distal His----Arg) have been investigated by flash photolysis at various temperatures above 0 degrees C. Sperm whale (Physter catodon) myoglobin and the isolated beta chains from normal adult hemoglobin have been used as references. In most reaction systems investigated the apparent extent of photolysis increases with temperature. For sperm whale myoglobin and the normal beta chains the increase is of the same magnitude and not correlated to the type of ligand used. On the contrary, for the two proteins lacking the distal histidine, the phenomenon is dependent on the size of the alkyl side chain of the ligand. The results, analyzed on the basis of the multibarrier model (Austin, R.H., K.W. Beeson, L. Eisenstein, H. Frauenfelder, and I.C. Gunsalus, 1975, Biochemistry, 16:5355-5373), suggest that the partition of the ligand molecules between the solvent and the heme pocket, occurring during the photolysis process, is primarily determined by interactions between the ligand and residues in the heme cavity rather than by diffusion through the protein matrix.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Cianuros
/
Hemoproteínas
Límite:
Animals
Idioma:
En
Revista:
Biophys J
Año:
1987
Tipo del documento:
Article
Pais de publicación:
Estados Unidos