H. Chassaigne et R. Lobinski, CHARACTERIZATION OF HORSE KIDNEY METALLOTHIONEIN ISOFORMS BY ELECTROSPRAY MS AND REVERSED-PHASE HPLC-ELECTROSPRAY MS, Analyst (London. 1877. Print), 123(10), 1998, pp. 2125-2130
Pneumatically assisted electrospray mass spectrometry (ESMS) in the di
rect mode and as a chromatographic detection technique was developed f
or the characterization of horse kidney metallothionein isoforms. Dire
ct analysis in an acidic medium showed the presence of three major and
five minor isoforms, the molecular masses of which were determined. T
he presence of the major isoforms (two of which matched the molecular
masses calculated according to the published sequences) was confirmed
by complexation with Cd at pH 4.0 and the determination of the stoichi
ometry of the complexes formed. Reversed-phase chromatography of Cd-7-
MT complexes (pH 6.0) gave two signals corresponding to the MT-1A and
MT-1B isoforms. A post-column acidification procedure was developed to
eliminate the possibility of artefacts associated with the formation
of mixed-metal (Cd, Zn) complexes during chromatography in neutral med
ia, and to improve the accuracy of the determination of the molecular
mass of MT isoforms.