Maltose Modifications

Such carba-disaccharides as validoxylamines A and B were synthesized as intermediary compounds in the total synthesis of validamycin antibiotics. Carba-disaccharides related to maltose, isomaltose, cellobiose, the trehaloses, and trehalosamine modifications have also been synthesized. 

P. L. Durette, L. Hough, and A. C. Richardson, The chemistry of maltose. Part II. Chemical modification at the reducing unit, J. Chem. Soc., Perkin Trans. 1 (1974) 88-96. 

Modification reactions that neutralize charges or introduce hydro-phobic residues usually lower the enzymic activity. The attachment of monosaccharides to alpha amylase by diazo coupling lowered the activity.12 This enzyme was stable to the reaction conditions for diazo coupling (pH 10,15 min at 0°) if the diazonium salts were not included in the solution. Inclusion of maltose in the reaction mixture to protect the active site lessened, but did not eliminate, the loss of activity, suggesting that the incorporation of hydrophobic structures, or the modification of a critical residue distant from the active site, was at least partly responsible for the loss of activity. 

The saccharification of potato starch with pure /3-amylase yields 61 % of maltose and not more. In a series of experiments we obtained as the mean value from the reduction, 61.1 %, and from the fermentation experiments, 60.8%. The reduction was (as in most experiments in this laboratory) determined by a modification of the iodometric method of... 

The simplest modification is to place a destabilizing amino acid at the N-terminal end according to the N-end rule (Varshavsky, 1992). This can be done by expressing the protein as a fusion protein, e.g. with maltose binding protein behind a cleavage site specific for a rare-cutting protease, such as factor Xq. In this case the N-terminal amino acid can be any amino acid except proline. 

The methods of methylation were first launched by the preparation of crystalline tetramethyl-glucose (7). Galactose (8), sucrose, and maltose (9) were subjected to methylation, and in 1906 the method was extended to determine die stmcture of the natural glucoside, salicin (10). Denham and Woodhouse (11) in 1910 were able to introduce methyl groups into cellulose. A modification of die mediylation method enabled it to be apphed to the preparation of glucosides and mediylated glucosides (12) and the simplification of work in such cases facilitated the eonstitutional study of sucrose, lactose, maltose, and cellobiose (13, 14, 15). 

Modifications have been made to the AMBER force field to improve the correlations between calculated and observed molecular properties of a-linked saccharides these led to refinements in solvation studies on maltose, a-, p- and Y-cyclodextrin and two larger cyclodextrins (DP 10 and 21). A molecular dynamics simulation investigation of the solvation patterns of the model disaccharide 4 in aqueous DMSO defined regions in which competition exists... 

For the production of AFB, special yeasts that produce lower amounts of ethanol or no ethanol at all can be used as well. This can be achieved either by selection of proper yeast strains that are not able to ferment maltose and maltotriose (e.g. Saccharomy-codes ludwigii) or by intentional modification of brewing yeast by random mutation or genetic engineering (Branyik, Silva, et al 2012 Burberg Zamkow, 2009). 

---