Glutamyl and 3-Aspartyl Peptide Linkages

The amino group in this structure could be an e-amino group of lysine or hydroxylysine or the terminal a-amino group of the second chain. In the latter case the /3- or 7-carboxyl peptide link would constitute a branching point rather than a cross-link. 

7-Glutamyl and 3-aspartyl links have been reported in many small peptides and these will be considered briefly before proceeding to the evidence for such links in proteins and, in particular, in collagen. 

Since that time a very considerable number of small peptides containing 7-glutamyl linkages have been reported. Some of those found very recently are included in Table III, together with those mentioned above. The recent papers refer to some naturally occurring 7-glutamyl peptides which had been found previously, and these are also reported by Wald-schmidt-Leitz and Reicheneder (1961), and Franzblau (1962). 

Glutathione or 7-glutamyl cysteinyl- Very widespread Harington and Mead 

7-L-Glu-)S-(prop-l-enyl)-L-cysteine Seeds of chives (1962) Matikkala and 

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