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Chymotrypsinogen: an activating enzyme in the mitochondrial membrane of rat submaxillary gland
M SinhaRoy1, D Bharadwaj, R N Hati
1Indian Institute of Chemical Biology, Jadavpur, Calcutta.
Abstract:
A peripheral membrane protease was purified from mitochondria of rat submaxillary gland. On non-denaturing PAGE the purified enzyme showed a single protein band with the enzyme activity. It yielded two protein bands with molecular weights of 39 KDa and 20 KDa on SDS-PAGE, indicating that the enzyme is composed of two protein components. The enzyme activity was strongly inhibited by SBTI, aprotinin and benzamidine. PMSF, TLCK and EDTA did not produce inhibition. The enzyme could hydrolyze different synthetic substrates having arginine at the P1 position with highest affinity for the substrate Bz-Phe-Val-Arg-p-nitroanilide was noted. The enzyme showed significant activation of chymotrypsinogen A.
Insights
Researchers purified a peripheral membrane protease from rat mitochondria. This enzyme, composed of two protein components, effectively hydrolyzes substrates with arginine at the P1 position and activates chymotrypsinogen A.
Area of Science:
- Biochemistry
- Mitochondrial Research
- Enzymology
Background:
- Mitochondria play crucial roles in cellular metabolism and signaling.
- Peripheral membrane proteins are essential for various cellular functions.
- Proteases are key enzymes involved in protein turnover and regulation.
Purpose of the Study:
- To purify and characterize a peripheral membrane protease from rat submaxillary gland mitochondria.
- To investigate the enzyme's composition, substrate specificity, and functional activity.
Main Methods:
- Mitochondrial isolation from rat submaxillary gland.
- Enzyme purification using non-denaturing and SDS-PAGE.
- Enzyme activity assays with synthetic substrates.
- Inhibition studies with protease inhibitors.
- Chymotrypsinogen A activation assay.
Main Results:
- A peripheral membrane protease was successfully purified, exhibiting a single band on non-denaturing PAGE.
- SDS-PAGE revealed the enzyme consists of two subunits (39 KDa and 20 KDa).
- The enzyme demonstrated strong hydrolysis of substrates with arginine at the P1 position, particularly Bz-Phe-Val-Arg-p-nitroanilide.
- Activity was inhibited by SBTI, aprotinin, and benzamidine, but not PMSF, TLCK, or EDTA.
- Significant activation of chymotrypsinogen A was observed.
Conclusions:
- The purified enzyme is a novel peripheral membrane protease from rat submaxillary gland mitochondria.
- Its two-subunit structure and substrate specificity suggest a role in specific proteolytic events.
- The enzyme's ability to activate chymotrypsinogen A indicates a potential role in coagulation or related pathways.