Zur Konstitution des Insulins

Abstract
Insulin was oxidized by means of performic acid, and the A and B fractions separated by continuous paper electrophoresis using N formic acid. Fraction A accounted for 37% and B for 60.6% of the total N. Each fraction was then analyzed as follows: (1) carboxyl end group determination according to the method of Grassman et al. (Chem. Ber. 86, 1477 (1953)); (2) estimation of amide groups; and (3) quantitative amino acid estimation by means of paper electrophoresis and chromatography. The results agreed well with the structure as proposed by Sanger. The only discrepancies were that in Fraction A there was a deficit of one valine and one isoleucine residue (based on mol. weight of 12,000); and that in fraction B an excess of proline was found. These discrepancies are discussed.