Peptides tryptamine-—36--------------------- tryptophan

Amines, Amino acids, peptides, e g tryptophan, tryptamine, peptides with terminal tryptophan groups... 

In our 1-hydroxyindole hypothesis, we had predicted that 5-hydroxy-tryptamines (serotonins) and 5-hydroxytryptophans were supplied from the 1-hydroxytryptophan residues in the tryptophans-containing peptides by the mediation of acids that are hnked with the TCA (Kreb s) cycle [2,5-7]. 

The reaction has been used to introduce a thiol group in the 2-position of a number of indole-containing compounds, in particular tryptamine, serotonin, skatole and tryptophan, the yields ranging from 65 to 95 per cent (727, 431). The single tryptophan residue of the pancreatic peptide hormone glucagon (29 amino acids) has also been modified by this method to the thioxindolylalanine derivative (727). 

Tryptophan peptides have also been found to be readily cyclized by PEE, for example, N-formyl-tryptophanyl-glycine methyl ester. When N-(N-acetylglycyl)-tryptamine (189) was treated with PPE, the inter-... 

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