Smith M L, Hjortsberg K, Ohlsson P I, Paul K G
Biomed Biochim Acta. 1983;42(7-8):805-11.
We have investigated the spontaneous release of heme from chromatographically homogeneous horseradish peroxidase A2 at varying temperature, pH and iron ligands. A "biphasic" rate of heme release was observed under all conditions. Upon further purification of HRP A2, a component was isolated that was homogeneous by polyacrylamide gel electrophoresis and exhibited a single first order rate of heme release. The rate of the release increased with pH and temperature, decreased in the presence of cyanide and increased slightly in the presence of fluoride. These results are consistent with the idea that the rate of heme release is a measure of the flexibility of the protein lining the heme "pocket" with iron bonding playing a secondary, though important role in heme-protein interactions.
我们研究了在不同温度、pH值和铁配体条件下，色谱纯辣根过氧化物酶A2中血红素的自发释放情况。在所有条件下均观察到血红素释放的“双相”速率。对HRP A2进一步纯化后，分离出一种通过聚丙烯酰胺凝胶电泳显示均一性且呈现单一一级血红素释放速率的组分。血红素释放速率随pH值和温度升高而增加，在氰化物存在下降低，在氟化物存在下略有增加。这些结果与以下观点一致，即血红素释放速率是衡量血红素“口袋”内衬蛋白质柔韧性的指标，而铁键合在血红素-蛋白质相互作用中虽起次要但重要的作用。
