SEPARATION OF METALLOTHIONEIN ISOFORMS OF MOUSE-LIVER CYTOSOL BY CAPILLARY-ZONE-ELECTROPHORESIS

Metallothionein (MT) isoforms of mouse liver cytosol were separated by capillary zone electrophoresis (CZE) using a polyacrylamide-coated tu be at neutral pH, samples prepared from non-treated, heat-treated, and ethanol-precipitated specimens were compared. The liver was homogeniz ed in three kinds of media, 0.25 M sucrose containing 100 mM Tris-HCl buffer at pH 7.4 (BS), BS containing 1% ascorbic acid (BS-C), and BS c ontaining 5 mM P-mercaptoethanol (BS-M). Mouse liver was used 24 h aft er subcutaneous injection of 50 mg Zn kg(-1). In the non-treated speci men of the cytosol fraction, the MT-2 isoform was separated in all thr ee media; while the MT-1 isoform was difficult to identify. In the eth anol-precipitated specimen, MT isoforms were separated well using eith er BS or BS-C. However, when BS-M was used, a small MT-2 peak was obta ined the MT-1 peak could not be identified. MT-1 isoform in the heat-t reated specimen was difficult to identify. In contrast, MT-2 isoform w as separated well in all three kinds of media. In the non-treated spec imen of the control liver cytosol, the MT-2 isoform was detected using all three media, the MT-1 peak was undetected. Based on these results , MT isoforms can be detected in the crude cytosol fraction of liver u sing CZE combined with a polyacrylamide-coated tube at neutral pH. (C) 1998 Elsevier Science B.V. All rights reserved.