Original Research Article
Year: 2018 | Month: October | Volume: 8 | Issue: 10 | Pages: 51-57
Progressive Study on the Physiological Role and Catalytic Properties of Buffalo Lung Cathepsin B
Sudhir K. Agarwal1, Ambika Ukil2, Shalini Singh3, Samir Sharma4
1Professor, 2,3Ph.D. Scholar, 4Associate Professor,
Department of Biochemistry, University of Lucknow, Lucknow-226007, India
Corresponding Author: Sudhir K. Agarwal
Physiological and catalytic properties of cathepsin B from water buffalo (Bubalus bubalis) lung, hitherto unstudied source/tissue, have been reported. The activity of the enzyme was optimal at physiological temperature (37°C) and the enzyme could withstand temperature shocks up to 37°C for 10-30 min without any significant loss of activity. Moreover the maximum activity was observed at pH 7.0 and the enzyme was fairly stable between pHs 3.5-6.75 for at least 20 min. Cathepsin B was most active at 2.5x10-3 M buffer concentration and lost its activity substantially as the buffer concentration was raised above optimum value. As the enzyme was highly stable between salt concentrations of 1.5x10-2 M to 3.5x10-2 M, it is recommended to store the enzyme in 0.05 M sodium phosphate or other buffer of equivalent ionic strength. The buffalo lung enzyme hydrolyzed Z-Phe-Arg-MCA (Vmax/Km=13.21) was found to be the most efficient substrate followed by Z-Arg-Arg-MCA, BANA and BAPNA. The preferred protein substrate for the enzyme is found to be haemoglobin. The enzyme also hydrolyzed other protein substrates such as bovine serum albumin, ovalbumin and casein, but to lesser extents. In contrast to prevailing opinion, it was concluded that cathepsin B can act for a limited period even at physiological temperature, pH and salt concentration before it is inactivated.
Key words: Lysosomal cysteine proteinase, Buffalo lung, Cathepsin B, Physiological parameters, Protein substrates.