Some observations on the amino-acid distribution of collagen, elastin and reticular tissue from different sources

Abstract

TRYPTOPHAN AND NICOTINAMIDE 281 amide are discussed. It could best be explained by a kind of catalytic action of tryptophan on the nicotinamide synthesis NOTE ADDED 7 APRIL 1949 Since this paper was submitted, Heidelberger, Abraham & Lepkowsky (1948) have reported feeding DL-tryptophan labelled in the fl-position of the side chain with 14C to rats; nicotinamide methochloride eliminated after ingestion contained a labelled C atom in the carboxylic acid group. This does not, however, prove, as is claimed by these authors, that 'the conversion proceeds in the same fashion in the rat as in Neurospora'. This work was carried out with a grant for expenses from the Medical Research Council to one of the authors (P.E.). We wish to express our thanks to Dr A. Emmanuelowa for culturing and classifying the E. coli