COPPER, ENZYMES, AND FERTILIZATION

Abstract

1. Nearly 37 per cent. of the copper sulphate added to sea-water is precipitated at once when the concentration is Cu = n/460.2. Two tenths c.c. normal Arbacia eggs in 75 minutes reduce the concentration of 14.8 c.c. of a Cu solution from n/1,460 to n/1,790.9.3. In this reduction the egg jelly or chorion is heavily involved.4. It was impossible to determine the quantities of copper absorbed by normal eggs and eggs without jelly because of an apparent secretion of copper by the eggs themselves.5. Therefore, the demonstration of copper in Arbacia eggs was undertaken. The copper was identified as cupric hydroxide, cupric cyanide, cupric ferrocyanide, copper xanthate, crystalline cupric sulphate, as metallic copper on tin-foil and aluminum, and finally by electrolytic precipitation under conditions under which copper and only copper could be deposited.6. The copper was localized in the egg directly by means of hæmatoxylin and the triple-nitrite of potassium-copper and lead. Indirectly it was localized by the analysis of egg secretions.7. The copper occurs chiefly in the egg pigment; the vitelline membrane and the chorion also contain copper. It is not a regular constituent of agglutinin precipitates, but was found constantly in precipitates of lipolysin.8. This association with lipolysin makes possible the localization of both copper and ferment in the cortex of the egg.9. The association of copper with lipolysin is not an isolated case. Copper was found also in preparations of pancreatic enzymes and pepsin.10. In eggs exposed to a n/180 Cu solution for twenty minutes the copper is widely diffused through the cytoplasm and concentrated in the chorion, the vitelline membrane, and the cortex.11. Approximately the amounts of copper normally present in 1 c.c. of Arbacia eggs are as follows:Unripe ovarian eggs = 17 µ gr.Ripe shed eggs = 175 µ gr.Fertilized eggs = 21 µ gr.12. From the preceding and other considerations it is suggested that copper, in general, may be more than an adventitious element, physiological only in pigments, and merely tolerated in all other connections.13. The association of copper with enzymes is explained as the outcome of some sort of union, very likely chemical, between enzymes or co-enzymes, or both, and the metal. It is also suggested that possibly the differences in the proportionality between silver and mercury effects, as well as the Danysz recovery after "poisoning," may be due to the distribution and subsequent redistribution of the metallic ions between enzymes and co-enzymes.14. The oligodynamic action of copper is explained as due to the inactivation of that fraction of the enzyme or co-enzyme which was not normally inactivated by the copper present in the first place. If inactivation is produced by silver, it is suggested that the total inactive enzyme or co-enzyme would be composed of two fractions—the one inactive because of the normal copper content, the other because of the silver added.15. It is suggested that the concentration of copper in the ovum at maturity may have something to do with limiting the growth of the egg; that the elimination of copper-bearing pigment during fertilization may indirectly restore or produce conditions essential for further growth and development.