1994 Volume 10 Issue 6 Pages 907-912
By combining reversed-phase high-performance liquid chromatography (RP-HPLC) with inductively coupled plasma mass spectrometry (ICPMS), the induction of two major metallothionein (MT) isoforms has been demonstrated for a cyanobacterium Anacystis nidulans R-2, cultured under a stress of Zn2+ or Cd2+. The two isoforms showed only a slight difference in the amino acid composition. Incubation of two Zn-MT isoforms in a medium containing Cd2+ led to a metal exchange, reflecting the higher affinity of MT to Cd2+ than to Zn2+. During this process the relative abundance of the two isoforms remained practically unchanged. The two isoforms were induced in a constant ratio by the Zn2+ dosage (1-20μM), while by the Cd2+ dosage (0.5-10μM) the ratio showed a change with the dose level. These results demonstrate the potential of the present RP-HPLC/ICPMS system to elucidate the function of MT isoforms.