Hill K A, Steiner S A, Castellino F J
Department of Chemistry, University of Notre Dame, IN 46556.
Biochem J. 1988 Apr 1;251(1):229-36. doi: 10.1042/bj2510229.
The paramagnetic effect of Mn2+ on the electron paramagnetic resonance spectrum of a nitroxide spin label covalently attached to the active-site serine residue of des-1-41-light chain bovine plasma-activated protein C, and situated at a distance of approximately 1.2 nm from this amino acid, has been utilized to estimate the distance on the enzyme surface between the single Mn2+ site and the free electron of the spin label. This distance has been found to be approx. 1.12 nm. A significant paramagnetic effect of Mn2+ on the spectrum of this same nitroxide spin label bound to activated protein C (APC) has been found. However, in this case distance calculations are complicated by the existence of a multiplicity of Mn2+ sites on APC. If it is assumed that a single Mn2+ site is responsible for the paramagnetic effect on the spectrum of the spin label, the interelectron distance on APC would be approx. 0.90 nm.
利用Mn²⁺对共价连接到去1-41轻链牛血浆活化蛋白C活性位点丝氨酸残基上、且与该氨基酸相距约1.2 nm的氮氧自旋标记电子顺磁共振谱的顺磁效应，来估算酶表面单个Mn²⁺位点与自旋标记自由电子之间的距离。已发现该距离约为1.12 nm。还发现Mn²⁺对结合到活化蛋白C（APC）上的同一氮氧自旋标记的谱有显著顺磁效应。然而，在这种情况下，由于APC上存在多个Mn²⁺位点，距离计算变得复杂。如果假设单个Mn²⁺位点对自旋标记谱的顺磁效应负责，那么APC上的电子间距离约为0.90 nm。
