metallothionein and Hemolysis

A review is presented of various aspects of copper (Cu) metabolism. The Cu absorption from the gastrointestinal tract in monogastric animals differs from that in ruminants. This is influenced by Cu binding compounds, sulphide production in the rumen, and molybdenum and zinc concentrations of the diet. Moreover, the valence of the Cu ions may influence the availability of Cu in the intestine. Metallothionein and lysosomes are involved in the accumulation of copper in the liver. The different findings in various Cu storage diseases may reflect different mechanisms of disease. Cu-induced liver cell damage and haemolysis may be the result of lipid peroxidation.

Topics: Animals; Cattle; Cattle Diseases; Ceruloplasmin; Chemical and Drug Induced Liver Injury; Copper; Digestive System; Dog Diseases; Dogs; Female; Hemolysis; Intestinal Absorption; Kinetics; Liver; Liver Diseases; Lysosomes; Metal Metabolism, Inborn Errors; Metallothionein; Mice; Rats; Rumen; Sheep; Sheep Diseases

Metallothionein (MT) is the protein that has been shown to bind heavy metals, scavenge free radicals, protect DNA from radiation damage, and alleviate disease symptoms. However, only very limited success has been achieved in expression and production of active recombinant metallothionein. In this study, human metallothionein 1A (hMT1A) was transformed into yeast Pichia pastoris for expression with secretion of the protein into the medium. The expression system was optimized to obtain the targeted protein in active form at 335 mg per litre culture. hMT1A showed the character of extreme instability in the experiment. High concentration, aeration and heavy metal ions are the main factors affecting hMT1A stability.

Topics: Carbon; Chlorides; Cysteine; Gene Expression; Hemolysis; Histidine; Humans; Metallothionein; Recombinant Proteins; Saccharomyces cerevisiae; Zinc Compounds

The detailed spectral changes observed in the absorption, circular dichroism (CD) and magnetic circular dichroism (MCD) spectra upon addition of Cd2+ to rat liver Cd,Zn-metallothionein (MT) are reported. Results from dialysis experiments clearly demonstrate that up to 8.6 mole equivalents of Cd2+ can be bound to this protein. The excess Cd2+ ions bound appear to have lower binding constants than those of the first seven Cd2+ ions bound. Red blood cell hemolysate (RBC) can compete with the metallothionein for all Cd2+ bound in excess of seven mole equivalents. Thus the RBC hemolysate method of estimating protein concentrations is shown to be correct when based upon complete loading of all binding sites in MT with Cd2+.

Topics: Animals; Cadmium; Circular Dichroism; Dialysis; Erythrocytes; Hemolysis; Liver; Metallothionein; Protein Binding; Rats; Spectrophotometry, Atomic