1935/01/01 by H. Jensen, E. Anthony Evans · 2 citations
Biochemistry, Genetics and Molecular Biology · #Cancer and biochemical research #Biochemical Acid Research Studies #Advanced Glycation End Products research
paper · doi:10.1016/s0021-9258(18)75301-5
openalex publication_date 1935/01/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/23
Certain evidence has been obtained that inactivation of insulin under various conditions, especially when this is reversible, occurs simultaneously with chemical changes involving the free amino groups of the protein molecule (2).Freudenberg and his coworkers, however, are of the opinion that no connection exist,s between free amino nitrogen and physiologica,l activity (3).The investigation of the nature of the free amino groups is of interest, not only as it contributes to our knowledge of the chemistry of insulin but in regard to its more general significance in the field of protein chemistry.It is generally assumed that the free amino groups of a protein are present as the c-amino groups of lysinc (4).In the case of insulin it is obvious that the amino nitrogen of the lysinc present cannot account for the total amino nitrogen of the hormone, since the latter is greater than the whole of the lysine nitrogen (5).When insulin is dissolved in ~/15 Na2HP04 and treated with phenylisocyanate, a product is obtained which retains approximately 5 per cent of the original activity of the hormone (1, 2).Under these conditions it is assumed that the hydroxyl (tyrosine) and the amino groups are principally attacked; the amino nitrogen, as measured by the Van Slyke method, has almost completely