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Multicatalytic proteinase in fish muscle
J J Sánchez1, E J Folco, L Busconi
1Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Argentina.
Abstract:
A partially active and a latent form of multicatalytic protease (MCP) were isolated from fish skeletal muscle. Both forms were inactive against protein substrates, but their activity against peptide substrates differed in one order of magnitude. The chymotrypsin-like activity of the partially active form was moderately stimulated by fatty acids and SDS, whereas its trypsin-like activity was inhibited by the same reagents. In contrast, both activities of the latent form were strongly stimulated by SDS. The chymotrypsin-like activity of the latent form was also stimulated by heating or high urea concentrations, whereas its trypsin-like activity did not change or was inhibited respectively by these treatments. These activation effects were irreversible. Pre-treatment of the latent form with SDS or urea in the absence of substrate led to its irreversible inactivation, whereas activation by pre-heating occurred in the presence or absence of substrate. These results suggest that MCP can exist in several active states with distinct properties. Studies on the distribution of MCP in fish tissues showed a much higher level of the enzyme in gonads than in any other tissue, suggesting a role of MCP in development.
Insights
Fish skeletal muscle contains a multicatalytic protease (MCP) with partially active and latent forms. These forms exhibit distinct activities and responses to stimuli like fatty acids and SDS, suggesting multiple active states and a role in development.
Area of Science:
- Biochemistry
- Enzymology
- Molecular Biology
Background:
- Multicatalytic protease (MCP) is found in fish skeletal muscle.
- MCP exists in different forms with varying activities.
- Understanding MCP's properties is crucial for its functional characterization.
Purpose of the Study:
- To isolate and characterize partially active and latent forms of fish MCP.
- To investigate the differential activities and activation mechanisms of MCP forms.
- To explore the distribution and potential role of MCP in fish tissues.
Main Methods:
- Isolation of partially active and latent MCP from fish skeletal muscle.
- Enzyme activity assays using peptide and protein substrates.
- Investigation of the effects of fatty acids, SDS, urea, and heat on enzyme activity.
- Analysis of MCP distribution across different fish tissues.
Main Results:
- Both MCP forms were inactive against protein substrates but showed differential activity against peptide substrates.
- Partially active MCP showed moderate stimulation/inhibition by fatty acids and SDS.
- Latent MCP exhibited strong stimulation by SDS, heat, and urea, with irreversible activation/inactivation observed.
- MCP levels were significantly higher in gonads compared to other tissues.
Conclusions:
- MCP can exist in multiple active states with distinct biochemical properties.
- Activation of latent MCP by SDS, heat, or urea leads to irreversible changes.
- The high concentration of MCP in gonads suggests a role in fish development.