Talk:Aldolase A

Untitled

Definition

Aldolase is an enzyme found throughout the body, particularly in muscles. Like all enzymes, it is needed to trigger specific chemical reactions. Aldolase helps muscle turn sugar into energy. Testing for aldolase is done to diagnose and monitor skeletal muscle diseases.

Purpose

Skeletal muscle diseases increase the aldolase level found in a person's blood. Skeletal muscles are those muscles attached to bones and whose contractions make those bones move. When the muscles are diseased or damaged, such as in muscular dystrophy, the cells deteriorate and break open. The contents of the cells, including aldolase, spill into the bloodstream. Measuring the amount of aldolase in the blood indicates the degree of muscle damage.

As muscles continue to deteriorate, aldolase levels decrease and eventually fall below normal. Less muscle means fewer cells and less aldolase.

Muscle weakness may be caused by neurologic as well as muscular problems. The measurement of aldolase levels can help pinpoint the cause. Aldolase levels will be normal where muscle weakness is caused by neurological disease, such as poliomyelitis or multiple sclerosis, but aldolase levels will be elevated in cases of muscular disease, such as muscular dystrophy.

Aldolase is also found in the liver and cardiac muscle of the heart. Damage or disease to these organs, such as chronic hepatitis or a heart attack, will also increase aldolase levels in the blood, but to a lesser degree.

Description

Aldolase is measured by mixing a person's serum with a substance with which aldolase is known to trigger a reaction. The end product of this reaction is measured, and, from that measurement, the amount of aldolase in the person's serum is determined.

mechanism

The mechanism picture is really confusing. Perhaps someone could number the steps? 129.31.72.52 19:55, 16 May 2007 (UTC)

I totally agree with this. Perhaps I can clear this up at a later date. 141.211.250.218 (talk) 01:40, 6 March 2009 (UTC)

For rabbit muscle aldolase A, Chung, Shi, Hopkins, Tolan & Allen (2001) suggested the catalytic base which deprotonates the C4-hydroxyl, leading to C-C bond cleavage, is Asp34. St-Jean, Lafrance-Vanasse, Liotard & Sygusch (2005) have proposed Glu 188 fills this role. Further discussion of the possible role of Glu 188 appears in Choi et al (2006). There is no Tyr residue in the active-site of the rabbit muscle enzyme. However, in the archaeal FBPA, Glu 188 is replaced by a Tyr residue, which could act as a proton donor (Lorentzen et al, 2003). Thus the identity of the base responsible for deprotonation of the C4-hydroxyl remains controversial. Note the discussion of the mechanism and the figure in the main article assign this role to a Tyr residue.

References

Choi KH, Lai V, Foster CE, Morris AJ, Tolan DR & Allen KN (2006). “New superfamily members identified for Schiff-base enzymes based on verification of catalytically essential residues”, Biochemistry, 45: 8546.

Chung KH, Shi J, Hopkins CE, Tolan DR & Allen KN (2001). “Snapshots of catalysis: the structure of fructose-1,6-(bis)phosphate aldolase covalently bound to the substrate dihydroxyacetone phosphate”, Biochemistry, 40:13868.

Lorentzen E, Pohl E, Zwart P, Stark A, Russell RB, Knura T, Hensel R & Siebers B (2003). “Crystal structure of an archaeal class I aldolase and the evolution of (βα)₈ barrel proteins”, J Biol Chem, 278: 47253.

St-Jean M, Lafrance-Vanasse J, Liotard B & Sygusch J (2005). “High resolution reaction intermediates of rabbit muscle fructose-1,6-bisphosphate aldolase: substrate cleavage and induced fit”, J Biol Chem, 280: 27262.

glyceraldehyde-3-phosphate

is rather gap than gad, i've never heard someone abbreviating it with gad... —Preceding unsigned comment added by 92.229.133.124 (talk) 08:28, 17 May 2009 (UTC)