Aldolase/glycerol phosphate dehydrogenase

Dihydroxyacetone phosphate (41) was prepared enzymatically from glycerol 1-phosphate (74) by the action of glycerol phosphate oxidase [177]. Analytical thin-layer chromatography was performed on silica gel plates using a 1 1 mixture of sat. ammonia-ethanol for development, and anisaldehyde stain for detection. The aldolases are commercially available or can be purified in accordance with published procedures [150]. Activity of aldolases (1 unit catalyzes cleavage of 1 pmol L-ketose 1-phosphates (43/45) per minute at 25 °C [150]) and amounts of 41 were determined photometrically by an assay coupled with glycerol phosphate dehydrogenase-catalyzed NADH oxidation [149]. 

Fig. 17. Nucleotidyltransferase substrate screening assay (NUSSA). A Nucleotide sugar-synthesizing nucleotidyltransferase (EC 2.7.7), B PPrdependent phosphofructokinase (EC 2.7.2.90), C Aldolase (EC 4.1.2.13), D Triose-phosphate isomerase (EC 5.3.1.1), E Glycerol-3-phosphate dehydrogenase (EC 1.1.1.8) [336]...

Fig. 6.1 Reaction scheme of the system under study. Glc, glucose HK, hexokinase PGI, phos-phoglucose isomerase PFK, phosphofructokinase ALD, aldolase TIM, triose phosphate isomerase G3PDH, glycerol 3-phosphate dehydrogenase 1,3BPG 1,3-bisphosphoglycerate PGK, phospho-glycerate kinase G6P, glucose 6-phosphate F6P, fructose 6-phosphate ATP, adenosine triphosphate ADP, adenosine diphosphate PEP, phospho-enolpyruvate F1,6BP, fructose 1,6-bisphosphate DHAP, dihydroxyacetone phosphate G3P, glycerol 3-phosphate GAP, glyceraldehyde...

This enzyme catalyses one of the intermediate steps of glycolysis. The reaction is not considered to be a rate-lunitmg step, but it may be used as an indicator reaction for the estimation of phosphofructokinase activity which is thought to be rate limiting. Serum levels of aldolase are elevated in diseases of skeletal muscle and in the presence of tumours in many tissues. Aldolase may be assayed by an ultraviolet method using triose phosphate isomerase as an auxiliary reaction and glycerol-3-phosphate dehydrogenase as an indicator reaction [219]. The trioses can be trapped as formed with the aid of... 

The usual precursor is dihydroxyacetone phosphate produced by the aldolase reaction of the glycolytic pathway. This is reduced by the NAD-linked glycerol-3-phosphate dehydrogenase ... 

DHAP is a glycolysis intermediate, whereas glyceraldehyde must be reduced by a mitochondrial enzyme, glyceraldehyde dehydrogenase, to glycerol, which is then subject to action by glycerol kinase in the liver. The aldolase seems to be the principal pathway of metabolizing fructose and depends on the initial phosphorylation step catalyzed by fructokinase, which produces fructose-l-phosphate. Fructokinase is defective in an inherited disorder, essential fructosuria. Fructose-l-phosphate aldolase is deficient in the hereditary disorder fructose intolerance. 

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