期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1982
卷号：79
期号：14
页码：4313-4316
DOI：10.1073/pnas.79.14.4313
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Amplitude-modulated phosphorescence/microwave double-resonance (AM-PMDR) spectra are reported for complexes of methylmercury(II) cation, designated CH3Hg(II), with tryptophan and glyceraldehyde-3-phosphate dehydrogenase (GPDHase; from rabbit muscle). Wavelength shifts are observed in the AM-PMDR spectra of CH3Hg(II)-tryptophan, which are obtained by microwave pumping in distinct zero-field D + E magnetic resonance transitions, demonstrating that AM-PMDR can be used to display selectively the phosphorescence spectra of structurally distinct complexes with different zero-field splittings. The AM-PMDR spectra accurately represent the phosphorescence of CH3Hg(II)-tryptophan. Binding of CH3Hg(II) to a cysteine site of GDPHase perturbs the luminescence of one of the two optically resolved tryptophan. The AM-PMDR spectrum of the perturbed tryptophan is obtained by microwave pumping of the D + E magnetic resonance signal, which can be observed optically only in the presence of a heavy atom perturbation. The resulting spectrum is broadened and shifted to the blue relative to the corresponding tryptophan phosphorescence spectrum of the uncomplexed enzyme. Comparison of the AM-PMDR spectra of CH3Hg(II)-tryptophan and CH3Hg(II)-GPDHase suggests that there are differences in the mechanisms of heavy atom perturbation in these complexes.
