Buzy A, Bracchi V, Sterjiades R, Chroboczek J, Thibault P, Gagnon J, Jouve H M, Hudry-Clergeon G
Institut de Biologie Structurale, CEA and CNRS, Grenoble, France.
J Protein Chem. 1995 Feb;14(2):59-72. doi: 10.1007/BF01888363.
The catalase of Proteus mirabilis PR, a peroxide-resistant (PR) mutant of Proteus mirabilis, binds strongly NADPH, which is a unique property among known bacterial catalases. The enzyme subunit consists of 484 amino acid residues for a mass of 55,647 daltons. The complete amino acid sequence was resolved through the combination of protein sequencing, mass spectrometry, and nucleotide sequencing of a PCR fragment. The sequence obtained was compared with that of other known catalases. Amino acids of the active site are all conserved as well as essential residues involved in NADPH binding. Among the amino acids interacting with the heme, a methionine sulfone was found at position 53, in place of a valine in most other catalases. The origin of oxidation of this methionine is unknown, but the presence of this modification could change iron accessibility by large substrates or inhibitors. This posttranslational modification was also demonstrated in the wild-type P. mirabilis catalase.
奇异变形杆菌PR（奇异变形杆菌的一种耐过氧化物（PR）突变体）的过氧化氢酶与NADPH紧密结合，这是已知细菌过氧化氢酶中独一无二的特性。该酶亚基由484个氨基酸残基组成，质量为55,647道尔顿。通过蛋白质测序、质谱分析以及PCR片段的核苷酸测序相结合，解析出了完整的氨基酸序列。将所得序列与其他已知过氧化氢酶的序列进行了比较。活性位点的氨基酸以及参与NADPH结合的必需残基均保守。在与血红素相互作用的氨基酸中，在第53位发现了甲硫氨酸砜，而在大多数其他过氧化氢酶中此处为缬氨酸。这种甲硫氨酸氧化的起源尚不清楚，但这种修饰的存在可能会改变大底物或抑制剂对铁的可及性。这种翻译后修饰在野生型奇异变形杆菌过氧化氢酶中也得到了证实。
