Author/Editor		Turk, Boris; Bieth, Joseph G; Bjork, Ingemar; Dolenc, Iztok; Turk, Dušan; Cimerman, Nina; Kos, Janko; Čolič, Adrijana; Stoka, Veronika; Turk, Vito
Title		Regulation of the activity of lysosomal cysteine proteinases by pH-induced inactivation and/or endogenous protein inhibitors, cystatins
Type		članek
Source		Biol Chem Hoppe Seyler
Vol. and No.		Letnik 376, št. 4
Publication year		1995
Volume		str. 225-30
Language		eng
Abstract		The kinetics of pH-induced inactivation of human cathepsins B and L was studied by conventional and stopped-flow methods. The inactivation of both enzymes was found to be an irreversible, first-order process. The inactivation rate constants increased exponentially with pH for both enzymes. From log kinac vs pH plots, 3.0 and 1.7 protons were calculated to be desorbed for pH-induced inactivation of cathepsins L and B. Cathepsin B was thus substantially more stable than cathepsin L (approximately 15-fold at pH 7.0 and 37 degrees C). Cathepsin B was efficiently inhibited by cystatin C at pH 7.4, whereas the inhibition by stefin B and high molecular weight kininogen was only moderate. In contrast, cathepsin L was efficiently inhibited by both chicken cystatin and stefin B at this pH kass approximately 3.3 x 10(7) m-1 s-1).
Descriptors		CYSTATINS CYSTEINE PROTEINASES LYSOSOMES CATHEPSIN B CATHEPSINS CHICKENS HYDROGEN-ION CONCENTRATION KINETICS