Evidence for a quaternary structure change in the cooperative binding of cyanide to ferrihemoglobin A. |
| |
Authors: | P F Coleman |
| |
Institution: | Stauffer Laboratory for Physical Chemistry Stanford University, Stanford, California 94305 USA |
| |
Abstract: | At pH 6.5 in a 0.05 bis-Tris-0.1 Cl? buffer, tetra aquo ferrihemoglobin A (HbA+) binds CN? with a Hill coefficient of n = 1.4. The Hill coefficient increases slightly and the average CN? affinity decreases in the presence of excess spin labeled triphosphate (SLTP). This is probably the result of the finding that the SLTP exhibits a twofold higher affinity for HbA+ than for tetra cyano HbA+. Over the course of heme saturation with CN?, a certain fraction of the SLTP is specifically released. This shows linkage between organic phosphate binding and heme ligation. These findings bear a marked resemblance to the ligand binding phenomena in hemoglobin A (HbA) and provide good evidence that under these experimental conditions, HbA+ is undergoing a quaternary conformation change as the hemes become saturated. |
| |
Keywords: | ferrihemoglobin A HbA hemoglobin A SLTP spin labeled triphosphate |
本文献已被 ScienceDirect 等数据库收录! |