The trifluoroacetylation of insulin

Fluorine nuclear magnetic resonance studies of trifluoroacetyl-insulin derivatives. Effect of pH on conformation and aggregation

“…Caled for C15H16F3O5: C, 48.00; , 4.30; F, 15.19. Found: C, 48.15; H, 4.33; F, 14.92. Nl-LysineB-29-trifluoroacetyl-insulin-octapeptide. Tritrifluoroacetyl-insulin (Levy and Paselk, 1973) (170 mg, 28 /tmol) was dissolved in bicarbonate buffer, pH 8.0. To this solution was added 14.2 ml of a Tos-PheCH2Cl-trypsin solution (pH 3.0, 1 mM CaCla, 1.2 mg/ml) and the reaction was stirred for 4 hr at 38°.…”

“…To this solution was added 14.2 ml of a Tos-PheCH2Cl-trypsin solution (pH 3.0, 1 mM CaCla, 1.2 mg/ml) and the reaction was stirred for 4 hr at 38°. The reaction mixture was chromatographed on Sephadex G-50, followed by chromatography on Sephadex G-10, as previously described (Levy and Paselk, 1973), to afford the TV'-trifluoroacetyl^^-octapeptide derivative.…”

“…Insulin hydrochloride (100 mg, 17.2 µ ) was treated with Tos-PheCHaCl-trypsin as previously described (Levy and Paselk, 1973) to afford desoctapeptide-insulin, which was purified on Sephadex G-25, eluting with 0.05 M ammonium acetate (pH 7.5). Trifluoroacetylation of the insulin derivative was effected in dimethylformamide with ethyl thioltrifluoroacetate (Levy and Paselk, 1973). The product was purified on Sephadex G-50, eluting with 0.05 M ammonium acetate (pH 7.5).…”

“…Various studies have been undertaken to explore this complex behavior, utilizing sedimentation velocity and equilibrium measurements (Jeffrey and Coates, 1966a,b;Pekar and Frank, 1972; Slobin and Carpenter, 1966;Fredericq, 1956), ultraviolet spectroscopy (Rupley et al, 1967;Frank et al, 1972;Lord et al, 1973), and optical rotatory dispersion and circular dichroism (Carpenter, 1966;Levy and Carpenter, 1970;Morris et al, 1968;Mercóla et al, 1967Mercóla et al, , 1972Ettinger and Timasheff, 1971). The availability of the high-resolution X-ray crystallographic data for zinc insulin (Blundell et al, 1972;Adams et al, 1969) further enables the analysis of the results obtained from these solution studies.…”

“…In an effort to further understand the effects of pH and solvent on the complex aggregation behavior of insulin as well as effects on conformation, the trifluoroacetyl moiety has been introduced at various points in the molecule (Figure 1; R = H or CF3CO1) to serve as an environmental probe utilizing 19F-nmr techniques. The derivatives obtained have been shown to possess high biological activity and immunoreactivity (Levy and Paselk, 1973;Geiger and Obermeier, 1973;Paselk and Levy, 1974). This report concerns the l9F-nmr spectra of several trifluoroacetyl-insulin derivatives and appropriate model compounds.…”