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Prochymosin activation by non-aspartic proteinases
V M Stepanov1, G I Lavrenova, Terent'eva EYu
1Institute of Genetics and Selection of Industrial Microorganism, Moscow, USSR.
FEBS Letters
|January 29, 1990
Summary
External proteinases can activate prochymosin into chymosin. Thermolysin and Legionella pneumophila metalloproteinase efficiently convert calf prochymosin, suggesting physiological importance of this intermolecular activation pathway.
Area of Science:
- Biochemistry
- Enzymology
- Protein Chemistry
Background:
- Prochymosin is the inactive precursor to chymosin, a key enzyme in milk coagulation.
- The conversion of prochymosin to chymosin typically occurs via an intramolecular cleavage.
- Understanding alternative activation pathways is crucial for biotechnological applications and comprehending enzyme regulation.
Purpose of the Study:
- To investigate the intermolecular activation of calf prochymosin by external proteinases.
- To identify specific proteinases and conditions that facilitate efficient prochymosin conversion.
- To explore the potential physiological relevance of intermolecular prochymosin activation.
Main Methods:
- Incubation of calf prochymosin with thermolysin at pH 5.05.
- Incubation of calf prochymosin with Legionella pneumophila metalloproteinase.
- Analysis of the resulting chymosin variants, including N-terminal sequencing and yield determination.
Main Results:
- Thermolysin successfully converted calf prochymosin into active Phe-chymosin, yielding 73% active enzyme.
- Phe-chymosin is characterized as being one amino acid longer at the N-terminus compared to standard chymosin.
- Legionella pneumophila metalloproteinase demonstrated even more effective activation of prochymosin.
- Optimal activation by external proteinases occurs within a pH range of 5.0-6.0, exposing a different cleavage site.
Conclusions:
- Intermolecular activation of prochymosin by specific metalloproteinases is feasible and efficient.
- The findings suggest that this alternative activation pathway may play a role in physiological processes.
- This research opens avenues for novel methods in chymosin production and enzyme engineering.