Kassner R J
Department of Chemistry, University of Illinois, Chicago 60680.
Biochim Biophys Acta. 1991 May 23;1058(1):8-12. doi: 10.1016/s0005-2728(05)80257-9.
The cytochromes c' bind CO, alkylisocyanides and CN- with rate and equilibrium constants which are 10(2)- to 10(6)-fold smaller than other high-spin hemoproteins. The decreased affinity for exogenous ligands is largely associated with steric interactions at the heme coordination site. While CO and alkylisocyanides bind noncooperatively to the dimeric Rhodospirillum molischianum cytochrome c', CO, alkylisocyanides and CN- appear to bind cooperatively to the dimeric Chromatium vinosum cytochrome c' due to a ligand-linked dimer-monomer dissociation equilibrium. The differences between the cytochromes c' are thought to be due to differences in amino acid residues near the heme coordination site and subunit interface.
细胞色素c'与一氧化碳、烷基异氰化物和氰根离子结合的速率和平衡常数比其他高自旋血红素蛋白小10²至10⁶倍。对外源配体亲和力的降低主要与血红素配位位点处的空间相互作用有关。虽然一氧化碳和烷基异氰化物与二聚体嗜糖红螺菌细胞色素c'非协同结合，但由于配体连接的二聚体-单体解离平衡，一氧化碳、烷基异氰化物和氰根离子似乎与二聚体葡萄酒色嗜盐菌细胞色素c'协同结合。细胞色素c'之间的差异被认为是由于血红素配位位点和亚基界面附近氨基酸残基的差异所致。
