FTC-insulin conjugates. II. Chemical characterization of fluorescein thiocarbamyl-insulin conjugates

A method is suggested for the chemical characterization of fluorescein thiocarbamyl conjugates used for the demonstration of antibodies in patients treated with insulin of animal origin.In order to determine accurately the amount of dye bound to insulin, the photometric characteristics of fluorescein, fluorescein isothiocyanate and fluorescein thiocarbamyl radical were studied and equations were derived for the calculation of dye content, dye protein ratio and fading of the dye during labelling. Protein determination was also modified because of the effect of light absorption of the fluorescein thiocarbamyl radical on the estimation.The method can be applied to the chemical characterization of any conjugate with appropriate modification.