Low-molecular-chromium, or nickel-binding substances from liver or milk of animals and their biological functions, especially in relation to detoxication and carcinogenesis of metals.

点击翻译按钮获取中文摘要

1. Low-molecular-weight (MW:1500)-chromium binding substances were purified from the liver and colostrum of dogs, rabbits and cows. They were composed of glutamic acid, glycine and cysteine with a Cr/amino-terminal residue ratio of 4:1. Chromium bound to them showed a lower toxicity and higher rates of urinary excretion than inorganic chromium compounds. Furthermore, some fraction of purified substances showed in vitro activities comparable to those of glucose tolerance factor in relation to insulin action.2. A low-molecular-weight (MW:900)-nickel-binding substance was also purified from the liver of rats. Nickel bound to it showed a lower cytotoxicity in the colony-formation tests using BALB/C 3T3 cells than inorganic nickel compounds. The substance.combined nickel in vitro to form the saturated ones with a Ni/molecule ration of 1:1. Some fractions of nickel were replaced with an essential element such as copper or zinc, but not with a non-essential element inclusing cadmium, lead and chromium.3. Organotin compounds, triphenyl and tributyltins, showed to inhibit insulin release from pancreas, collagen-induced aggregation of platelets, O_2^- production and chemotaxis of leukocytes, and histamine release from mast cells. A common mechanism seemed to be an inhibition of the stimulusresponse coupling in the cell membrane. The same mechanism was supposed to be acting in the anti-malignant tumor activity in vivo and in vitro of dibutyltin compounds.4. Nickel bound to the low-molecular-nickel-binding substance showed a strong carcinogenic activitiy to cultured BALB/C 3T3 cells in contrast to no induction of transformation by inorganic nickel compounds.