Application of mercury cold vapor atomic fluorescence spectrometry to the characterization of mercury-accessible -SH groups in native proteins

A new analytical approach has been applied to the determination and characterization of mercury-accessible -SH groups in pure native protein samples (ovalbumin, hemoglobin, glyceraldehyde-3-phosphate dehydrogenase, aldolase, pyruvate kinase, hexokinase, lactate dehydrogenase, alcohol dehydrogenase, creatine phosphokinase, lysozyme, and cytochrome c). The method is based on the selective reduction of Hg-II in the presence of Hg-II-thiol complexes with alkaline sodium tetrahydroborate, to give Hg-0 in a continuous flow reaction system coupled with atomic fluorescence spectrometric (AFS) detection. The method is fast and specific and allows one to work with nanomole amounts of a single protein without any preliminary incubation and without any separation of Hg-II from thiol-complexed mercury. The meaning of the results obtained in the determination of the accessible -SH groups in native proteins by using chemical probes is discussed. (C) 1999 Academic Press.