77026-80-3 77026-81-4 L-Prolinamide, N-((tetrahydro-5-oxo-2-furanyl)carbonyl)-L-histidyl- N-((Tetrahydro-5-oxo-2-furanyl)carbonyl)-L-histidyl-L-prolinamide gamma-Butyrolactone-gamma-carbonyl-his-pronh2