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Journal article
Oxidation inhibits substrate proteolysis by calpain I but not autolysis
Journal of Biological Chemistry, Vol.272(2), pp.2005-2012
272
1997
PMID: 8999893
Web of Science ID: WOS:A1997WD05800091
Abstract
In this study, the effects of oxidation on calpain I autolysis and calpain-mediated proteolysis were examined. Calpain I was incubated with increasing concentrations of free calcium in the presence or absence of oxidant, and autolytic conversion of both the 80- and 30-kDa subunits was measured by immunoblotting utilizing monoclonal antibodies which recognize both autolyzed and non-autolyzed forms of each subunit, respectively. Autolytic conversion of the 80-kDa subunit of calpain I was not detected until free calcium concentration was greater than 40 μM, whereas autolysis of the 30-kDa subunit did not occur until the free calcium concentration was greater than 100 μM. In addition, autolytic conversion of either the 80- or 30-kDa subunit was not inhibited by the presence of oxidant. Calpain I activity was measured using the fluorescent peptide N-succinyl-L-leucyl-L-leucyl-L-valyl-L-tyrosine-7-amido-4-methylcoumarin or the microtubule-associated protein tau as substrate. Calpain I was found to have proteolytic activity at free calcium concentrations below that required for autolysis. Calpain I activity was strongly inhibited by oxidant at all calcium concentrations studied, suggesting that proteolytic activity of both the non-autolyzed 80-kDa and autolyzed 76-kDa forms was susceptible to oxidation. Interestingly, whereas oxidation did not inhibit autolytic conversion, the presence of high substrate concentrations did result in a significant reduction of autolysis without altering calpain proteolytic activity. Calpain I activity that had been inhibited by the presence of oxidant was recovered immediately by addition of the reducing agent dithiothreitol.
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- Title
- Oxidation inhibits substrate proteolysis by calpain I but not autolysis
- Publication Details
- Journal of Biological Chemistry, Vol.272(2), pp.2005-2012
- Resource Type
- Journal article
- Publisher
- Elsevier Inc.; United States
- Series
- 272
- Copyright
- This is an Open Access article under the CC BY license
- Identifiers
- WOS:A1997WD05800091; 99380090776706600
- Academic Unit
- Biology; Hal Marcus College of Science and Engineering
- Language
- English