obsolete 3-benzyl-3,6 -bis(glutathione)- 6-(hydroxymethyl)-diketopiperazine gamma-glutamylcyclotransferase activity (obsolete GO:0102636)
OBSOLETE. Catalysis of the reaction: 3-benzyl-3,6 -bis(glutathione)- 6-(hydroxymethyl)-diketopiperazine = 3-benzyl-3,6 -bis(cysteinylglycine)- 6-(hydroxymethyl)-diketopiperazine + 2 5-oxo-L-prolinate.