EFFECTS OF CONTAMINATING PROTEINASE ACTIVITIES IN CHONDROITINASE AND KERATANASE PREPARATIONS UPON THE HISTOCHEMICAL RESULTS OBTAINED BY THEIR DIGESTION PROCEDURES

Abstract

In the present study the effects of contaminating proteinase activities in commercially available preparations of chondroitinases and keratanase were tested upon the histochemical results obtained by their digestion procedures. Tissue sections from the ear and tracheal cartilages, aorta, umbilical cord and cornea of mammals were subjected to staining procedures after prior digestion with the enzyme solutions with or without proteinase inhibitors. In a substantial number of tissue sections examined, the addition of proteinase inhibitors to the enzyme solutions appeared to suppress the decline in intensity of the staining reaction induced by the enzyme digestions. These results are taken to indicate that the commercially available preparations of chondroitinases and keratanase contain significant amounts of contaminating proteinases. When these enzyme preparations are employed as histochemical reagents the addition of proteinase inhibitors to the enzyme solutions is indispensable for precise localization of the enzyme substrates in tissues.