Different tissue distributions of two types of thiol proteinase inhibitors from rat liver and epidermis.

The concentrations of two types of endogenous inhibitors of thiol proteinases were determined in soluble extracts of various rat tissues by means of a sensitive enzyme immunoassay method, which consisted of solid-phase immobilized anti-rat liver inhibitor or anti-rat epidermal inhibitor and antibodies labeled with horseradish peroxidase. The minimum detectable amounts of inhibitors from liver and epidermis were 30 pg and 3 pg/assay, respectively. The tissue distributions of the epidermal and liver-type inhibitors were found to differ. The liver-type inhibitor was found to be widely distributed in various tissues at levels of 76-420 ng/mg protein, whereas the epidermal-type inhibitor was found at high levels in the skin, tongue, esophagus, stomach, intestine, and vagina, but at quite low levels in other tissues tested.