label: (L-glutamyl)(n)-gamma-L-glutamyl-L-glutamyl-[protein] + L-glutamate => (L-glutamyl)(n+1)-gamma-L-glutamyl-L-glutamyl-[protein] + H2O
label_lc: (l-glutamyl)(n)-gamma-l-glutamyl-l-glutamyl-[protein] + l-glutamate => (l-glutamyl)(n+1)-gamma-l-glutamyl-l-glutamyl-[protein] + h2o