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Do you know? Why do lysinase enzymes from animals and plants have similar structures but different functions?
Leucyl aminopeptidase (LAPs) is an enzyme widely present in different biological kingdoms. Its main function is to catalyze the hydrolysis of the amino-terminal amino acids of peptide chains and proteins. Surprisingly, although lysinase enzymes in animals and plants share many structural similarities, they show significant differences in biological functions and reaction mechanisms.
Enzyme structure and active site
Lysinase requires divalent metal cations for enzymatic activity, which is true in both animal and plant LAPs. These enzymes have the highest activity at pH 8 and 60°C. The active sites of LAPs are structurally similar. For example, studies have confirmed the similarity between the active sites of cattle lysinase and E. coli PepA.
These enzymes rely on metal ions such as Mn2+, Mg2+ and Zn2+ during the catalytic process, and these Enzymes usually exist as hexamers in the body.
Differences in biological functions
Traditionally, LAP-A has been viewed as an indirect housekeeping gene critical for protein turnover. However, as research progressed, it was discovered that this enzyme plays a regulatory role in the immune response of tomato plants.
Background of plant immune response
Plants must be able to respond quickly to biotic and abiotic stresses, such as pathogen attacks or insect infestations. Under these conditions, plants initiate specific signal transduction pathways. For example, tissue damage caused by chewing insects such as tobacco hornworms activates the octacarbonic acid pathway to synthesize a variety of signaling molecules, which subsequently regulate the expression of related genes.
The role of the octacarbonic acid pathway
LAP-A, as a product of the octacarbonic acid pathway, plays a regulatory role in maintaining and extending plant injury responses.
For example, in a series of experiments, the researchers found that when the LAP-A gene was silenced, injured tomato plants were significantly less resistant to insect damage, and the expression of their late genes was also suppressed relative to wild-type plants. .
Function of osmoregulation
It is worth noting that LAP is also expressed in some marine organisms, and its main purpose is to deal with the threat of osmotic pressure in high-salt environments. In order to maintain intracellular amino acid concentrations, under the danger signal of high salt, these enzymes begin to catalyze proteins to release amino acids into the cell.
Conclusion
In summary, although lysinase enzymes in animals and plants show striking structural similarities, they exhibit completely different properties in terms of physiological functions and mechanisms. This phenomenon has triggered our profound thinking about the evolution of life and its biochemical mechanisms. Do you think these small structural differences hint at the infinite possibilities of life forms in adapting to the environment?
