Zinc is an important metallic constituent of the enzyme
carboxypeptidase A, a pancreatic enzyme active in protein degradation. Zinc is
found in highest concentration in the liver, with lesser amounts found in the
pancreas, kidney, and pituitary gland. Zinc absorption occurs primarily in the
small intestine. Zinc-binding ligand molecules act to transport zinc across the
mucosal cells of the intestine, where it is picked up by albumin molecules for
transport to the liver and other organs.
Zinc is a constituent of the enzyme carbonic anhydrase.
This enzyme is, in turn, a constituent of red blood cells and gastric juices,
and plays an important role in the deposition of calcium salts in teeth and
The enzyme alcohol dehydrogenase contains zinc and is
essential for the conversion of alcohol to an aldehyde, thereby facilitating
alcohol metabolism in the liver. The function of this enzyme and its
relationship to the development of liver cirrhosis is conspicuously tied to
characteristic zinc deficiencies in alcoholic patients.
Zinc is found in other enzymes as well, including lactic
dehydrogenase (active in glycolysis), alkaline phosphatase (active in
maintaining phosphate levels near bone), and glutamic dehydrogenase (found in
Zinc is important as a structural constituent for RNA
proteins and is essential for the proper activity of the RNA synthesizing
enzyme RNA polymerase. Zinc also plays a role in metabolism and three
dimensional structure of DNA.
Zinc is found in alpha-macroglobulin, an important
protein in the bodys immune system. This globulin firmly binds about 30%
of plasma albumin, which functions primarily as a transport protein.
Zinc appears to be a cofactor in the synthesis and
degradation of collagen, and has effects in reproduction and healing.
Factors which can impair zinc absorption include calcium,
fiber, copper, iron, and various diseases, such as Crohns disease.
SUMMARY OF METABOLIC FUNCTIONS
Functions in more than 80 enzymes and hormones
Essential in RNA and DNA synthesis
Necessary for growth
Necessary for release of vitamin A from the