Muscle aldolase

Sygusch, J., Beaudry, D., Allaire, M. Molecular architecture of rabbit skeletal muscle aldolase at 2.7 A resolution. Proe. Natl. Aead. Sei. USA 84 ... 

R)-2-Hydroxy-3-thiopropanal (Table 5), which could not be isolated from the reaction mixture, can be directly converted into 6-thio-D-wnimo-2-hexulose (7%) and 6-thio-L-xylo-2-hexulose (93 %) via rabbit muscle aldolase catalyzed condensation with dihydroxyacetonephos-phate28. 

The class I FruA isolated from rabbit muscle aldolase (RAMA) is the aldolase employed for preparative synthesis in the widest sense, owing to its commercial availability and useful specific activity of 20 U mg . Its operative stability in solution is limiting, but the more robust homologous enzyme from Staphylococcus carnosus has been cloned for overexpression [87], which offers unusual stability for synthetic purposes. Recently, it was shown that less polar substrates may be converted as highly concentrated water-in-oil emulsions [88]. 

The hexose phosphate, fructose-1,6-diphosphate, is split by aldolase into two triose phosphates glyceraldehyde-3-phosphate and dihydroxyacetone phosphate. Aldolase consists of four 40-kDa subunits. Three tissue-specific forms exist in human tissues aldolase A (ubiquitous and very active in the muscle), aldolase B (liver, kidney, and small intestine), and aldolase C (specific to the brain). These three isozymes have nearly the same molecular size but differ in substrate specificity,... 

Ozawa, H. (1967) Bridging reagent for protein. II. The reaction of N,N -polymethylenebis(iodoacetamide) with cysteine and rabbit muscle aldolase./. Biochem. (Tokyo) 62, 531. 

The essentially nonreversible formation of D-fructose 1-phosphate in the muscle-aldolase system is probably attributable to thermodynamic stabilization. D-Fructose 1-phosphate can form a stable pyranose structure, whereas D-fructose 1,6-diphosphate can exist only in the less stable furanose or acyclic forms.72(,) Only when the cleavage products are removed is the monophosphate effectively split under the influence of aldolase. 

D-afe-o-Heptulose (sedoheptulose) (XXXVII) has been synthesized from D-erythrose (XXXVIII) plus triose phosphate, using an aldolase preparation from peas.169 Aldolases from yeast and from rat liver also form heptu-lose phosphate from these substrates.7S(o) 170(a) Crystalline muscle aldolase causes the formation of L-jrZwco-heptulose (XXXVIIa) from a mixture of L-erythrose (XXXVTIIa) and hexose diphosphate.170(b)... 

Muscle aldolase deficiency. The first patient with muscle aldolase deficiency was identified in 1996 this young boy suffered from a hemolytic trait but also... 

RAMA rabbit muscle aldolase (fructose-1,6-bis-phosphate aldolase)... 

Zhang Z., Post C.B., Smith D.L. Amide hydrogen exchange determined by mass spectrometry application to rabbit muscle aldolase. Biochemistry 1996, 35, 779—791. 

Scheme 28. RAMA = Rabbit muscle aldolase TPI = Triose phosphate isomerase...

These enzymes have been found in all plant and animal tissues examined and are absent only from a few specialized bacteria. Three closely related isoenzymes are found in vertebrates.185 186 The much studied rabbit muscle aldolase A is a 158-kDa protein tetramer of identical peptide chains.186 187 Aldolase B, which is lacking in hereditary fructose intolerance, predominates in liver and isoenzyme C in brain.185... 

Furthermore, the catalytic efficiency (K t/KM) of 84G3 for this substrate, 3.3 X 105 s-1M-1, is comparable with the efficiency of natural muscle aldolase, 4.9 X 104 s 1M 1, in the retro-aldolization of its substrate fructose 1, 6-bisphosphate (Morris and Tolan, 1994). However, these two enzymes use different substrates, and the rates were recorded at different temperatures (22°C for 84G3, 4°C for the natural aldolase). Despite this, we believe that it will be possible to develop a catalytic antibody that, under identical conditions, has a faster cat and lower KM than a natural enzyme for the same substrate. 

Isolation and structure of eucomin and eucomol. Tetrahedron Lett 36 3479 Borysenko CW, Spaltenstein A, Straub JA, Whitesides GM (1989) The synthesis of aldose sugars from half-protected dialdehydes using rabbit muscle aldolase. J Am Chem Soc 111 9275... 

Scheme 5.22. Chemoenzymatic synthesis of (+) exo-breviocomin by rabbit muscle aldolase (RAMA). Pase = phosphatase.

Active site selective reagents can be classified in various manners. One way is to divide them according to how they react (Table IX). In such a classification one finds substrates that can be covalently attached by chemical treatment of the enzyme while it is catalyzing some change in the substrate. An example is the reaction of functional amino groups by the enzyme muscle aldolase acting on glyceraldehyde and reduced by cyanoboro-hydride (16). 

The amino acid sequence results clearly Imply a unique sequence for each of the enzymes examined, and there is no decisive evidence for the existence among GAPDH s of tissue-specific isozymes that differ in primary sequence despite reports of the occurrence of multiple electrophoretic forms in several different organisms (40, 41)- In no case was it demonstrated that these multiple forms are the products of different genes, and it is entirely possible that electrophoretically different tetra-mers may have arisen by amide loss [as in the case of muscle aldolases (4 ) ] or through differential binding of NAD (41). 

Since the work of Sibley and Fleisher (S22) made it plain that elevation of serum aldolase activity occurred quite characteristically in other diseases besides myopathy, such as in hemolytic anemia and in acute hepatitis, it would be most useful to know that in muscular dystrophy the increased serum aldolase was indeed derived from the diseased muscle. Direct demonstration of this origin has been provided (D14) by showing that in 5 of 10 patients with muscular dystrophy the femoral venous return had a higher serum aldolase activity than the femoral arterial supply to the diseased muscles of the lower limb. Further strong support is given by the discovery that serum contains two aldolases (S8) with different substrate requirements (H5) whereby colorimetric methods have been devised for the separate assay of each (S5). These are 1,6-diphosphofructoaldolase ( muscle aldolase) and 1-phosphofruc-toaldolase ( liver aldolase). The ratio in mammalian tissues of muscle to liver aldolase activity is 40 in skeletal and cardiac muscle, 12-25 in spleen, lung, and red cells, and only unity in liver and kidney (S6, S7). The serum activities of both are equally elevated in hepatitis, but in muscular dystrophy and in muscle crush injury only that of muscle aldolase is raised (S4, S6) indeed, the ratio of serum activity of muscle to liver aldolase has been reported as about unity in healthy individuals and in patients with virus hepatitis, but as about 26 in a series of 14... 

Diphosphofructoaldolase is a soluble glycolytic enzyme especially abundant in skeletal muscle, occurring also in the myocardium and to a lesser extent in liver and erythrocytes, so that hemolysis of blood specimens elevates the serum aldolase activity and must therefore be avoided. The molecular weight of muscle aldolase is 147,000-180,000 (DIO), Its function is specifically the reversible splitting of D-fructose-1,6-diphosphate (FDP) into equimolecular amounts of the trioses D-glyceralde-hyde-3-phosphate (G-3-P) and dihydroxyacetone phosphate (DAP). 

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