68223-96-1 Boc-leu-gly-arg-pna Butyloxycarbonyl-leucyl-glycyl-arginine-4-nitroanilide Butyloxycarbonyl-leucyl-glycyl-arginyl-para-nitroanilide L-Argininamide, N-((1,1-dimethylethoxy)carbonyl)-L-leucylglycyl-N-(4-nitrophenyl)- N-tert-Butoxycarbonyl-L-leucyl-L-glycyl-L-arginine-p-nitroaniline