Aldolases rabbit muscle aldolase

There are two distinct groups of aldolases. Type I aldolases, found in higher plants and animals, require no metal cofactor and catalyze aldol addition via Schiff base formation between the lysiae S-amino group of the enzyme and a carbonyl group of the substrate. Class II aldolases are found primarily ia microorganisms and utilize a divalent ziac to activate the electrophilic component of the reaction. The most studied aldolases are fmctose-1,6-diphosphate (FDP) enzymes from rabbit muscle, rabbit muscle adolase (RAMA), and a Zn " -containing aldolase from E. coli. In vivo these enzymes catalyze the reversible reaction of D-glyceraldehyde-3-phosphate [591-57-1] (G-3-P) and dihydroxyacetone phosphate [57-04-5] (DHAP). 

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]. 

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 aldol reaction is of fundamental importance in organic chemistry and has been used as a key reaction in the synthesis of many complex natural products. There are biocatalysts for this reaction (aldolases) and one (rabbit muscle... 

Among multitryptophan proteins emitting light around 330 nm, we have observed the largest red-edge effect (estimated from the difference between the maxima of the fluorescence spectra obtained at 290- and 305-nm excitation) for papain in the active and inactive forms (13 and 10 nm, respectively). Large shifts were also observed for rabbit muscle asparagyl- and valyl-RNA synthetases (8 nm). For rabbit aldolase A, the observed shift was 6 nm, for skeletal muscle myosin, 4.5 nm, for chymotrypsin, 2.5 nm, and for carbonic... 

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. 

DHAP-dependent aldolases have also been used as key step in the synthesis of several complex natural products starting from achiral precursors. Thus, the sex pheromone (+)-exo-brevicomin can be synthesized in a multi-step route starting with the stereospecific aldol addition between DHAP and 5-oxohexanal or its 5-dithiane-protected analog catalyzed by FBPA from rabbit muscle ( RAMA ) as the key step by which the absolute configuration of the target is estabUshed (Scheme 4.16) [40]. 

The original preparation of 6-C-perfluoroalkyl-D-fructose has been reported. The first step of this synthesis is the perfluoroalkylation of acrolein acetal. The key step of the synthesis is an aldol condensation between D-3-fluoroalkylglyceraldehyde and dihydroxyacetone phosphate, with RAMA as biocatalyst (RAMA is an aldolase found in rabbit muscles) (Figure 6.43). ... 

Reaction of ribose 5-phosphate 116 with dihydroxyacetone phosphate, catalyzed by fructose 1,6-diphosphate aldolase from rabbit muscle (RAMA) affords the ketose diphosphate 117. Dihydroxyacetone phosphate was formed in situ from fructose 1,6-diphosphate by action of RAMA and triose phosphate isome-rase (TPI). The diphosphate 117 was dephosphorylated enzymatically using acid phosphatase, and the ketose 118 was reduced directly into the a-C-manno-side 119 by treatment with bistrimethylsilyltrifluoroacetamide, trimethylsilyl-triflate and triethylsilane (Scheme 28) [45]. 

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... 

Fig. 2. Schematic representation of substrate binding and C-C bond formation for the class I fructose 1,6-bisphosphate aldolase from rabbit muscle...

Representatives of all kinds have been explored for synthetic applications while mechanistic investigations were mainly focussed on the distinct FruA enzymes isolated from rabbit muscle [196] and yeast [197,198]. For mechanistic reasons, all DHAP aldolases appear to be highly specific for the donor component DHAP [199], and only a few isosteric replacements of the ester oxygen for sulfur (46), nitrogen (47), or methylene carbon (48) were found to be tolerable in preparative experiments (Fig. 7) [200,201], Earlier assay results [202] that had indicated activity also for a racemic methyl-branched DHAP analog 53 are now considered to be artefactual [203]. Dihydroxyacetone sulfate 50 has been shown to be covalently bound via Schiff base formation, but apparently no a-deprotonation occurred as neither H/D-exchange nor C-C... 

Fig. 8. Stability of the rhamnulose 1-phosphate aldolase from Escherichia coli (RhuA) vs. that of the fructose 1,6-bisphosphate aldolase from rabbit muscle (FruA) in phosphate buffer (pH 7.2 25°C ca. 1 Uml ) a) RhuA b) O RhuA, 30% EtOH c) RhuA, 50% DMSO d) FruA...

Of the several aldolases that are now commercially available, the rabbit muscle enzyme with a useful specific activity of 20 Umg-1 still remains the most cost-efficient catalyst for preparative work, although the reported higher stability of the Staphylococcus carnosus enzyme is a challenge [252,285], Literally hundreds of aldehydes have so far been tested successfully by enzymatic... 

Fructose 1,6-biphosphate aldolase from rabbit muscle in nature reversibly catalyzes the addition of dihydroxyacetone phosphate (DHAP) to D-glyceraldehyde 3-phosphate. The tolerance of this DHAP-dependent enzyme towards various aldehyde acceptors made it a versatile tool in the synthesis of monosaccharides and sugar analogs [188], but also of alkaloids [189] and other natural products. For example, the enzyme-mediated aldol reaction of DHAP and an aldehyde is a key step in the total synthesis of the microbial elicitor (—)-syringolide 2 (Fig. 35a) [190]. 

For the described approach, it is important to note that aldolases of different origin were tested and that, in contrast to L-rhamnulose-1-phosphate aldolase (RhuA), the D-fructose-1,6-biphosphate aldolase from rabbit muscle and L-fucu-lose-1-phosphate aldolase from E. coli were not active for DHAP/(R)-N- and (S)-iV-Cbz-prolinal condensation. Since RhuA accepts both, (S)-N- and (R)-N-Cbz prolinals, the chemo-enzymatic synthesis of both, hyacinthacines A and A2 isomers could be achieved. In conclusion, the origin and the particular enzyme itself... 

Carbon-carbon bond-forming reactions are some of the most important transformations in organic chemistry. Sobolov et al. [33] reported that CLCs of fructose 1,6-diphosphate aldolase from rabbit muscle are much more stable than the soluble enzyme. The synthetic potential of these CLCs was demonstrated by the preparation of a series of compounds shown in Fig. 10. 

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... 

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