Quantification of metallothioneins by a silver-saturation method
Journal Article
·
· Toxicol. Appl. Pharmacol.; (United States)
The binding of Ag+ to metallothionein (MT) was investigated, and a Ag-saturation assay was developed for the measurement of MT in tissues. When samples of purified hepatic Zn-MT or Cd-MT were titrated with Ag+ followed by hemolysate-heat treatment, it was found that saturation of MT occurred at 17 to 18 g-atoms Ag+/mol protein. The rank order of potencies of metals to displace Ag+ from 110mAg-labeled Ag-MT was Ag+ greater than Cu2+ greater than Cd2+ greater than Hg2+ greater than Zn2+ at pH 8.5 in 0.5 M glycine buffer. When a Ag-saturation (Ag-hem) assay was compared with a Cd-saturation (Cd-hem) technique, excellent correspondence was obtained in the measurement of MT from various sources including purified Zn-MT (II), MT in human kidney and liver tissue samples, hepatic MT in Cd-injected adult rats, and renal MT in Hg-injected adult rats. However, in cases where significant amounts of Cu-MT were present, such as in the livers of Cu-injected rats or in the kidneys of Cd-injected rats, the Cd-hem assay consistently underestimated the MT concentrations compared to the Ag-hem method. This is attributed to the inability of Cd to displace Cu effectively from MT at pH 8.5. Thus the Cd-hem assay is not recommended for the measurement of metallothioneins containing a high Cu content. Under such conditions, the Ag-hem method seems superior.
- Research Organization:
- Univ. of Western Ontario, London
- OSTI ID:
- 5615343
- Journal Information:
- Toxicol. Appl. Pharmacol.; (United States), Journal Name: Toxicol. Appl. Pharmacol.; (United States) Vol. 3; ISSN TXAPA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
560301* -- Chemicals Metabolism & Toxicology-- Cells-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMALS
BODY
CADMIUM
CHEMICAL ANALYSIS
CHEMICAL BONDS
COPPER
DIGESTIVE SYSTEM
DISTRIBUTION
ELEMENTS
GLANDS
LIVER
MAMMALS
MEASURING METHODS
MERCURY
METALLOPROTEINS
METALLOTHIONEIN
METALS
ORGANIC COMPOUNDS
ORGANS
PROTEINS
QUANTITATIVE CHEMICAL ANALYSIS
RATS
RODENTS
SILVER
TISSUE DISTRIBUTION
TRANSITION ELEMENTS
VERTEBRATES
ZINC
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMALS
BODY
CADMIUM
CHEMICAL ANALYSIS
CHEMICAL BONDS
COPPER
DIGESTIVE SYSTEM
DISTRIBUTION
ELEMENTS
GLANDS
LIVER
MAMMALS
MEASURING METHODS
MERCURY
METALLOPROTEINS
METALLOTHIONEIN
METALS
ORGANIC COMPOUNDS
ORGANS
PROTEINS
QUANTITATIVE CHEMICAL ANALYSIS
RATS
RODENTS
SILVER
TISSUE DISTRIBUTION
TRANSITION ELEMENTS
VERTEBRATES
ZINC