Purification and Characterization of Cathepsin L from Skeletal Muscle of the Lizard Agama stellio stellio

S. Al-Jassabi

Biological Sciences Department, Yarmouk University, Irbid, Jordan; fax: (02) 274-725; E-mail: sjassabis@hotmail.com

Received October 12, 1998; Revision received October 19, 1999

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Cathepsin L from skeletal muscle of the lizard Agama stellio stellio was purified to homogeneity by ion-exchange and gel-permeation chromatography. The molecular weight of the cathepsin L is estimated to be 34 kD, and its isoelectric point is 5.5. The cathepsin L has a pH optimum of 6.1, requires a thiol-reducing reagent for activation, and is inhibited by cysteine protease inhibitors. The K_m and k_cat values for Z-Phe-Arg-MCA as substrate are 1.4 µM and 6.2 sec^-1, respectively. This enzyme readily hydrolyzes proteins such as insulin B chain, hemoglobin, and serum albumin.

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KEY WORDS: cathepsin L, Agama stellio stellio, cysteine protease

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