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

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.