Brunet J E, Pulgar M
Instituto de Química, Universidad Catolica de Valparaiso, Chile.
Biochim Biophys Acta. 1993 Nov 10;1203(1):171-4. doi: 10.1016/0167-4838(93)90053-t.
The local motion of protoporphyrin IX in the heme pocket of horseradish peroxidase has been studied using fluorescence methods. The temperature dependence of the anisotropy and lifetime of a protoporphyrin IX-apo-horseradish peroxidase complex, dissolved in a solution of 80% glycerol and 20% buffer (0.1 M phosphate, pH 7.4), was determined. Anisotropy data were analyzed in terms of the thermal coefficient of the frictional resistance to fluorophore movement. The resultant 'Y' plot was characterized by three distinct slopes. The slope corresponding to the lowest temperature regime agreed with the value obtained for fluorophores not complexed with protein. The slope corresponding to an intermediate temperature was lower indicating a larger resistance to porphyrin rotation. At higher temperatures this resistance to rotation diminished as evidenced by the increased slope. These results are contrasted with those obtained with the protoporphyrin IX-apomyoglobin complex.
已使用荧光方法研究了辣根过氧化物酶血红素口袋中原卟啉IX的局部运动。测定了溶解在80%甘油和20%缓冲液（0.1 M磷酸盐，pH 7.4）溶液中的原卟啉IX-脱辅基辣根过氧化物酶复合物的各向异性和寿命的温度依赖性。根据荧光团运动的摩擦阻力的热系数分析各向异性数据。所得的“Y”图具有三个不同的斜率。对应于最低温度范围的斜率与未与蛋白质复合的荧光团获得的值一致。对应于中间温度的斜率较低，表明对卟啉旋转的阻力较大。在较高温度下，这种旋转阻力减小，这由斜率增加证明。这些结果与用原卟啉IX-脱辅基肌红蛋白复合物获得的结果形成对比。
