Aldolase A

Aldolase A is an enzyme which catalyses one of the aldol reactions: The substrate, fructose 1,6-bisphosphate (F-1,6-BP) is broken down into glyceraldehyde 3-phosphate and dihydroxyacetone phosphate (DHAP). This reaction is a part of glycolysis. Three aldolase isozymes (A, B, and C), encoded by three different genes, are differentially expressed during development. Aldolase A is found in the developing embryo and is produced in even greater amounts in adult muscle. Aldolase A expression is repressed in adult liver, kidney and intestine and similar to aldolase C levels in brain and other nervous tissue. Aldolase A deficiency has been associated with myopathy and hemolytic anemia. Alternative splicing of this gene results in multiple transcript variants which encode the same protein.

The numbering of the carbon atoms indicates the fate of the carbons according to their position in fructose 6-phosphate.

Mechanism
In mammalian aldolase the key catylitic amino acid residues involved in the reaction are lysine and tyrosine. The tyrosine acts as an efficient hydrogen acceptor while the lysine covalently binds and stabilizes the intermediates. Many bacteria use two magnesium ions in place of the lysine.