Ionization of the heme propionate substituents in pseudomonad cytochromes c-551.
Ionization of the heme propionate substituents in pseudomonad cytochromes c-551.
复制标题
假单胞菌细胞色素 c-551 中丙酸血红素取代基的电离。
DOI：
10.1016/0014-5793(92)81105-u
复制
发表时间：
1992
期刊：
影响因子：
3.5
通讯作者：
Timkovich,R
中科院分区：
文献类型：
--
作者：
Cai,M;Timkovich,R
假单胞菌细胞色素c-551中的血红素丙酸取代基部分被蛋白质结构中的多肽折叠所掩埋，并参与几个氢键。这些基团的电离行为一直是人们感兴趣的，因为血红素的氧化电位随pH值的变化的方式，可以平行的丙酸离子化。这些基团的电离pKa的已确定通过以下的NMR化学位移附近的质子作为探针的电离状态的丙酸酯。在铜绿假单胞菌c-551中，13-丙酸酯（IUB-IUPAC卟啉命名法）的pKa为3.1，17-丙酸酯的pKa为7.2。在同源的施氏假单胞菌c-551中，各自的丙酸盐的pKa值均为3.0。
The heme propionate substituents inPseudomonascytochromec‐551 are partially buried by folds of polypeptide in the structure of the protein, and are involved in several hydrogen bonds. The ionization behavior of these groups has been of interest because the oxidation potential of the heme changes with pH in a manner that may parallel ionization of a propionate. The ionization pKa's of these groups have been determined by following the NMR chemical shifts of nearby protons acting as probes of the ionization state of the propionates. InPseudomonas aeruginosa c‐551 the13‐propionate (IUB‐IUPAC porphyrin nomenclature) has been assigned a pKaof 3.1, and the17‐propionate a pKaof 7.2. In the homologousPseudomonas stutzeri c‐551, the respective propionates both have pKavalues of 3.0.