Abstract
^<14>C-Labelled leupeptin, Ac-L-[U-14C]-leucyl-L-leucyl-L-argininal, with a specific radioactivity of 20.9 mCi/mmol was prepared by a semisynthetic procedure in which L-leucyl-L-argininal dibutylacetal obtained by an enzymatic cleavage of leupeptin dibutyl-acetal with thermolysin was employed as a key compound. The chemical and radiochemical purities of the labelled leupeptin were found to be over 99% by high performance liquid chromatography using radioisotope and ultraviolet detectors.
