Studies on alanine aminotransferase in nematodes

Area of Science:

• Biochemistry
• Parasitology
• Enzymology

Background:

• L-alanine aminotransferase (AAT) is crucial in amino acid metabolism.
• AAT exists as mitochondrial and cytosolic isoenzymes in mammals.
• The presence and properties of AAT in nematodes are not well-characterized.

Purpose of the Study:

• To investigate the presence and characteristics of L-alanine aminotransferase in various nematode species.
• To compare nematode AAT with mammalian AAT, particularly rat liver enzyme.
• To explore potential differences in enzymatic activity, substrate specificity, and stability.

Main Methods:

• Enzyme assays were performed on extracts from gastrointestinal, free-living, and entomophagous nematodes.
• Characterization of mitochondrial and cytosolic isoenzymes.
• In vitro assays to determine L-alanine synthesis and catabolism capacities.
• Investigation of D-alanine transamination.
• Analysis of thermal stability and response to protective reagents for *H. contortus* enzyme.

Main Results:

• L-alanine aminotransferase was detected in diverse nematode groups.
• Nematode AAT exists as mitochondrial and cytosolic forms, analogous to mammals.
• Most nematode enzymes showed a higher capacity for L-alanine synthesis versus catabolism, contrasting with rat liver AAT.
• Certain gastrointestinal nematodes exhibited low-rate D-alanine transamination.
• *H. contortus* cytosolic AAT displayed significant differences in thermal stability and reagent response compared to mammalian AAT.

Conclusions:

• Nematodes possess distinct L-alanine aminotransferase isoenzymes with unique metabolic roles.
• Nematode AAT exhibits differential substrate utilization and stability compared to mammalian counterparts.
• These findings highlight potential targets for nematode-specific drug development.