Sandbox Reserved 346: Difference between revisions

[[Image:Ast-reaction final copy.JPG|right|thumb|upright=3|Figure 2-Transamination reaction of L-aspartate and alpha-ketoglutarate catalyzed by aspartate aminotransferase]]

AST catalyzes the reversible transamination of the alpha-amino group from L-aspartate to alpha-ketoglutarate forming oxaloacetate and alpha-ketoglutamate<ref name ="AST ROLES AND STRUCTURE"/>. This reactivity is lower in E.coli than in higher eukaryotes, and has broader substrate specificity<ref name ="AST Structure"/>. However, the reaction takes place in the same way<ref name ="AST Structure"/>. Upon introduction of an amino acid substrate, a new Schiff base will form between it and the PLP  cofactor<ref name ="AST Structure"/><ref name ="TRANSAMINATION">PMID:5450225</ref>. This causes the amino acid to lose a hydrogen and form a quinoid intermediate, and reprotanation takes place resulting in a ketimine<ref name ="AST Structure"/><ref name ="TRANSAMINATION"/>. Next, the structure is hydrolyzed forming an alpha-keto acid and pyridoxamine phosphate<ref name ="TRANSAMINATION"/>. 2-methyl aspartate acts as an inhibitor of AST when it forms a Schiif base with the PLP cofactor, rather than aspartate<ref name ="TRANSAMINATION"/><ref name ="AST Structure"/>. This results in the process stopping at the step prior to the alpha protein elimination<ref name ="TRANSAMINATION"/><ref name ="AST Structure"/>.