Alanine and aspartate aminotransferase and glutamine-cycling pathway: Their roles in pathogenesis of metabolic syndrome

Table 1 Overview about liver aminotransferases alanine and aspartate

ALT or GPT

Catalyzes the reversible transamination1 between alanine and 2-oxoglutarate to form pyruvate and glutamate: L-alanine + 2-oxoglutarate = pyruvate + L-glutamate

ALT has both degradative and biosynthetic roles in the glutamate cycling

ALT participates in cellular nitrogen metabolism and also in liver gluconeogenesis starting with precursors transported from skeletal muscles

ALT is present in tissues including liver, kidney, heart, and skeletal muscle.

AST or GOT

Catalyzes the reversible transamination between L-aspartate and 2-oxoglutarate to form oxaloacetate and glutamate: L-alanine + 2-oxoglutarate

L-aspartate + 2-oxoglutarate = oxaloacetate + L-glutamate

Cytosolic AST (GOT 1 catalyzes the reversible reaction of oxaloacetate and glutamate to form aspartate and 2-oxoglutarate (alpha-ketoglutarate)

AST has two isoforms: cytoplasmatic and mitochondrial

¹Transaminase: A subclass of enzymes that catalyze the transfer of an amino group from a donor (generally an amino acid) to an acceptor (generally 2 keto acid) in a cyclic process using pyridoxal phosphate as a cofactor. ALT: Alanine aminotransferase; AST: Aspartate aminotransferase; GPT: Glutamate pyruvate transaminase; GOT: Glutamate oxaloacetate transaminase.