Isolation of an effective debriding agent from the stems of pineapple plants.

The stem of the pineapple plant contains, in addition to a number of proteases, particularly bromelain, a non-proteolytic component which is responsible for the complete bridement of experimental burns by an "enzymatic dissection" between the viable native and the non-viable denatured burn tissue. With very little scraping, using a tongue depressor, all of the eschar can be removed and a bed suitable for grafting results. This "Escharase" has a molecular weight of 45,000 daltons and is a trimer made up of three identical subunits weighing 15,000 daltons each; it has an isoelectric point of pH 6.04 and has no hydrolytic enzyme activity against normal protein substrates or various glycosaminoglycan substrates. It can be concentrated by membrane ultrafiltration in a molecular weight range between 30,000 and 50,000 daltons and be purified by isoelectric focusing. The biological activity of the Escharase is not dependent on sulfhydryl groups nor upon the contaminating bromelain activity. The Escharase activity varies enormously from preparation to preparation, but the ultrafiltration procedure tends to concentrate Escharase activity to a fairly constant amount.