Some Physical-Chemical Variables Affecting Insulin Migration in vitro I. Electrophoresis. ∗

Abstract

Summary and conclusions

In confirmation of our previous studies(4), it is again noted that TRIS in this in vitro system does not function as an inert buffer, and that physical-chemical interaction with insulin does occur on Whatman 3 mm paper. The degree of interaction is greater in the buffer system containing the greater concentration of TRIS. The beta-gamma globulin binding of radioinsulin in the growth-onset diabetics is not as completely dissociated by TRIS as that observed in the maturity-onset or insulin-resistant diabetic patients. This observation suggests that insulin is more tightly bound to the beta-gamma globulins appearing in the serum of growth-onset diabetics as compared to more freely dissociated binding by the beta-gamma globulins of the maturity-onset or insulin-resistant diabetic patients in this study. An alternative suggestion is that a difference in the nature of the chemical bond which is dissociated by the TRIS occurs in the sera of growth-onset diabetics. Since displacement of radioinsulin from beta-gamma globulin binding sites by TRIS was evident on Whatman 3 mm paper, but not on cellulose acetate, we conclude that there was a network interaction between the radioinsulin, TRIS, and the Whatman 3 mm supporting medium, despite apparent saturation of insulin binding sites with carrier insulin. We wish to present this as a physical-chemical observation in this particular in vitro system, and we feel that it would be unwise to attempt to draw physiological conclusions from this data.