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On the substrate specificity of cathepsin L
Acta Biologica Et Medica Germanica
|January 1, 1981
Summary
Cathepsin L exhibits broad protein degradation at low pH but restricted specificity at neutral pH. Its synthetic substrates are not specific, as they are also hydrolyzed by other proteases like cathepsin B.
Area of Science:
- Biochemistry
- Enzymology
- Proteolysis
Background:
- Cathepsin L (EC 3.4.22.15) is a cysteine protease implicated in various biological processes.
- Understanding its substrate specificity and kinetic properties is crucial for elucidating its physiological roles.
Purpose of the Study:
- To investigate the maximal protein hydrolysis by cathepsin L as a function of pH.
- To evaluate the specificity of known synthetic substrates for cathepsin L.
Main Methods:
- Assessing protein degradation by cathepsin L across a range of pH values.
- Determining kinetic constants for synthetic substrates: Bz-Arg-NH2, Z-Lys-OPhNO2, and Z-Phe-Arg-NMec.
Main Results:
- Cathepsin L demonstrates broad substrate specificity for overall protein degradation at pH < 6.0.
- At pH 7.0 and 7.5, cathepsin L exhibits restricted specificity, cleaving specific peptide bonds.
- Known synthetic substrates are hydrolyzed by cathepsin L, but also by cathepsin B and other proteinases, indicating lack of complete specificity.
Conclusions:
- The pH significantly influences the substrate specificity of cathepsin L.
- Current synthetic substrates are inadequate for selective assays of cathepsin L activity due to cross-reactivity with other proteases.