344550-92-1Relevant academic research and scientific papers
α-Galactobiosyl units: Thermodynamics and kinetics of their formation by transglycosylations catalysed by the GH36 α-galactosidase from Thermotoga maritima
Borisova, Anna S.,Ivanen, Dina R.,Bobrov, Kirill S.,Eneyskaya, Elena V.,Rychkov, Georgy N.,Sandgren, Mats,Kulminskaya, Anna A.,Sinnott, Michael L.,Shabalin, Konstantin A.
supporting information, p. 115 - 121 (2015/02/18)
Broad regioselectivity of α-galactosidase from Thermotoga maritima (TmGal36A) is a limiting factor for application of the enzyme in the directed synthesis of oligogalactosides. However, this property can be used as a convenient tool in studies of thermodynamics of a glycosidic bond. Here, a novel approach to energy difference estimation is suggested. Both transglycosylation and hydrolysis of three types of galactosidic linkages were investigated using total kinetics of formation and hydrolysis of pNP-galactobiosides catalysed by monomeric glycoside hydrolase family 36 α-galactosidase from T. maritima, a retaining exo-acting glycoside hydrolase. We have estimated transition state free energy differences between the 1,2- and 1,3-linkage (ΔΔG?0 values were equal 5.34 ± 0.85 kJ/mol) and between 1,6-linkage and 1,3-linkage (ΔΔG?0 = 1.46 ± 0.23 kJ/mol) in pNP-galactobiosides over the course of the reaction catalysed by TmGal36A. Using the free energy difference for formation and hydrolysis of glycosidic linkages (ΔΔG?F - ΔΔG?H), we found that the 1,2-linkage was 2.93 ± 0.47 kJ/mol higher in free energy than the 1,3-linkage, and the 1,6-linkage 4.44 ± 0.71 kJ/mol lower.
A strategy for chemical synthesis of selectively methyl-esterified oligomers of galacturonic acid
Clausen, Mads H.,Jorgensen, Malene R.,Thorsen, Jesper,Madsen, Robert
, p. 543 - 551 (2007/10/03)
The synthesis of monomethyl-esterified trigalacturonans 1-3 is described as part of a general strategy towards pectic oligosaccharides. The necessary monomeric building blocks were all prepared on a large scale from galactose pentaacetate. The glycosylations were carried out between galactose glycosyl donors and acceptors using the n-pentenyl glycosylation technique. Yields of the desired α-anomers were in the 50 to 74% range. The trigalactans thus obtained were then subjected to oxidation at C-6. Depending on the protecting group at this position the oxidation either produced the carboxylic acid or the corresponding methyl ester. Hereby, oligomers of galacturonic acid can be prepared with methyl esters introduced in a regiocontrolled fashion.
