Bertini I, Capozzi F, Dikiy A, Happe B, Luchinat C, Timmis K N
Department of Chemistry, University of Florence, Italy.
Biochem Biophys Res Commun. 1995 Oct 24;215(3):855-60. doi: 10.1006/bbrc.1995.2542.
The 1H NMR spectra of an aromatic ring-cleaving extradiol dioxygenase, 2,2',3-trihydroxybiphenyl dioxygenase of the dibenzofuran-degrading bacterium Sphingomonas sp. strain RW1, are reported. In the catalytically active reduced form of the monomeric enzyme (MW = 32 kDa), three broad strongly downfield shifted signals were observed, two of which disappeared in D2O solution. Their shifts and linewidths are consistent with ring NH and meta-like protons of coordinated histidines. These signals show strong sensitivity to the presence of the substrate. The oxidized form of the enzyme shows no hyperfine shifted signals. It is suggested that the high spin Fe(II) ion present in the active form of the enzyme is coordinated by at least two histidines. This is the first report of hyperfine shifted NMR signals being detected for an extradiol dioxygenase.
报道了二苯并呋喃降解细菌鞘氨醇单胞菌属菌株RW1的一种芳香环裂解双加氧酶——2,2',3-三羟基联苯双加氧酶的1H NMR谱。在单体酶（分子量 = 32 kDa）的催化活性还原形式中，观察到三个宽的强向低场位移信号，其中两个在D2O溶液中消失。它们的位移和线宽与配位组氨酸的环NH和类似间位的质子一致。这些信号对底物的存在表现出强烈的敏感性。酶的氧化形式没有超精细位移信号。表明酶活性形式中存在的高自旋Fe(II)离子至少由两个组氨酸配位。这是首次报道在一种双加氧酶中检测到超精细位移的NMR信号。
