Galactose degradation

Bissett, D. L. and Anderson, R. L. 1974A. Genetic evidence for the physiological significance of the D-tagatose 6-phosphate pathway of lactose and D-galactose degradation in Staphylococcus aureus. J. Bacteriol. 119, 698-704. 

Fekete E, Karaffa L, Sandor E, Banyai I, Seiboth B, Gyemant G, Sepsi A, Szentirmai A, Kubicek CP (2004) The alternative D-galactose degrading pathway of Aspergillus nidulans proceeds via L-sorbose. Arch Microbiol 181 35-44... 

Sucralose is quite stable to heat over a wide range of pH. However, the pure white dry powder, when stored at high temperature, can discolor owing to release of small quantities of HCl. This can be remedied by blending it with maltodextrin (93) and other diluents. The commercial product can be a powder or a 25% concentrate in water, buffered at pH 4.4. The latter solution may be stored for up to one year at 40°C. At lower pH, there is minimal decomposition. For example, in a pH 3.0 cola carbonated soft drink stored at 40°C, there is less than 10% decomposition after six months. The degradation products are reported to be the respective chlorinated monosaccharides, 4-chloro-4-deoxy-galactose (13) and l,6-dichloro-l,6-dideoxy-fmctose (14) (94). 

Conversion of the aldehyde into a nitrile is accomplished by treatment of an aldose with hydroxvlamine to give an oxime (Section 19.8), followed by dehydration of the oxJme with acetic anhydride. The Wohl degradation does not give particularly high yields of chain-shortened aldoses, but the reaction is general for all aldopentoses and aldohexoses. For example, D-galactose is converted by Wohl degradation into n-lyxose. 

The reaction rate increased with temperature. The hydrolysis rate of AG at temperatures lower than 70 °C was very slow. At 80 °C, only complete release of arabinose was achieved, but partially hydrolyzed galactose residue was left. The conversion of AG was 43%. A complete conversion of AG to monomers was achieved at 90 and 100 °C. After the hydrolysis at 100 °C, traces of degradation products such as furfural were observed. For this reason, the temperature for AG hydrolysis shall not exceed 100 °C. 

SPS could be degraded by the cruder, aaikalus preparation Pectinex Ultra-SP, giving a product consisting mostly of the monomeric sugars xylose, galactose, fucose, arabinose and... 

DGBP Lactalbumins Lysozymes Galactose activation (369) Lactose biosynthesis Catalyze degradation of peptidoglycan, e.g. of bacterial cell walls (370,371)... 

On Ca +-form columns, some separation of monosaccharides is possible and, for the separation of galactose and glucose in dairy products, this is the column of choice. The separation of several disaccharides, such as sucrose plus maltose plus lactose, in sweetened dairy products cannot be accomplished on single-resin columns, however, and separation on amine-modified silica gel or on dual-resin columns " is recommended. These columns are capable of separating the five major food sugars, namely, D-glucose, D-fructose, sucrose, maltose, and lactose, but are subject to rapid degradation if proper precautions are not used (see Section II,2,a). 

Horak J, Wolf DH (1997) Catabolite inactivation of the galactose transporter in the yeast Saccharomyces cerevisiae Ubiquitination, endocytosis and degradation in the vaccuole. J Bacteriol 179 1541-1549... 

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