Chang C S, Sinclair R, Khalid S, Yamazaki I, Nakamura S, Powers L
National Center for the Design of Molecular Function, Utah State University, Logan 84322-4630.
Biochemistry. 1993 Mar 23;32(11):2780-6. doi: 10.1021/bi00062a007.
Native lactoperoxidase, compound III, and the reduced forms (at pH 6 and 9) were studied using X-ray absorption spectroscopy (XAS). Native lactoperoxidase has four pyrrole nitrogen ligands at an average distance of 2.04 +/- 0.01 A, a proximal ligand at 1.91 +/- 0.02 A, and a sixth (distal) ligand at 2.16 +/- 0.03 A. Lactoperoxidase native enzyme has a first coordination shell structure that is similar to that of native lignin peroxidase [Sinclair, R., Yamazaki, I., Bumpus, J., Brock, B., Chang, C.-S., Albo, A., & Powers, L. (1992) Biochemistry 31, 4892-4900] and different from that of horseradish peroxidase [Chance, B., Powers, L., Ching, Y., Poulos, T., Schonbaum, G., Yamazaki, I., & Paul, K. (1984) Arch. Biochem. Biophys. 235, 596-611]. Similarly, lactoperoxidase compound III resembles lignin peroxidase compound III. The five-coordinated ferrous form was stable at pH 9, but at pH 6 it was rapidly converted to the six-coordinated form with a distal ligand at 2.18 +/- 0.03 A. No evidence typical of changes in spin state was obtained at the different pH values.
利用X射线吸收光谱法（XAS）对天然乳过氧化物酶、化合物III以及还原形式（在pH 6和pH 9条件下）进行了研究。天然乳过氧化物酶有四个吡咯氮配体，平均距离为2.04±0.01 Å，一个近端配体距离为1.91±0.02 Å，还有一个第六（远端）配体距离为2.16±0.03 Å。天然乳过氧化物酶的第一配位层结构与天然木质素过氧化物酶的相似[辛克莱尔，R.，山崎，I.，邦普斯，J.，布罗克，B.，张，C.-S.，阿尔博，A.，&鲍尔斯，L.（1992年）《生物化学》31，4892 - 4900]，与辣根过氧化物酶的不同[钱斯，B.，鲍尔斯，L.，程，Y.，普oulos，T.，舍恩鲍姆，G.，山崎，I.，&保罗，K.（1984年）《生物化学与生物物理学报》235，596 - 611]。同样，乳过氧化物酶化合物III类似于木质素过氧化物酶化合物III。五配位亚铁形式在pH 9时稳定，但在pH 6时会迅速转化为六配位形式，其远端配体距离为2.18±0.03 Å。在不同pH值下未获得自旋状态变化的典型证据。
