Galactose labeling

Further characterization of the galactose-labeled product was carried... 

Problem 25,13 Draw /3-o-galactopyranose and jS-D-mannopyranose in their more stable chair conformations. Label each ring substituent as either axial or equatorial. Which would you expect to be more stable, galactose or mannose ... 

Also the pattern of release of labelled galactose brought about by the exo-galactanase corresponded exactly to that observed for the carrier galactan. At the end of the en me incubations, less than 1% of the dissolved radioactivity remained at the origin of the TLC,... 

The following protocol was used by Wilchek and Bayer (1987) to label cell-surface galactose residues. 

The reactivity and use of biocytin-hydrazide is similar to that described for biotin-hydrazide in Section 3, this chapter. The following protocol for labeling glycoproteins at oxidized carbohydrate (galactose) sites is from Bayer and Wilchek (1992). 

To each ml of glycoprotein solution, add 30 pi of neuraminidase (1 unit/ml as supplied by Behringwerke AF), then 30 pi of galactose oxidase (previously dissolved at 100 units/ml in the labeling buffer of step 1), and finally 100 pi of the biocytin hydrazide solution. 

Bayer, E.A., Ben-Hur, H., and Wilchek, M. (1988) Biocytin hydrazide—a selective label for sialic acids, galactose, and other sugars in glycoconjugates using avidin-biotin technology. Anal. Biochem. 170, 271-281. 

Topper and Stetten (T2) fed rats on galactose isotopically labeled with Cu on carbon atom 1. They found that the glycogen formed in the liver was isotopically labeled and 70% of the C14 was on C-l of the glucose units. They concluded that galactose could not be split into 2 triose units which would then recombine, but that a Walden-type inversion must occur at C-4. 

E2. Eisenberg, F., Isselbacher, K. J., and Kalckar, H. M., Studies on metabolism of carbon-14-labelled galactose in a galactosemie individual. Science 125, 116-117 (1957). 

Shinkai et al. described the synthesis of dendritic saccharide sensors based on a PAMAM dendrimer labeled with eight boronic acid residues [183]. The dendritic compound showed enhanced binding affinity for D-galactose and d-fructose. The fact that the dendritic boronic acid functions as a saccharide sponge is ascribed primarily to the cooperative action of two boronic acids to form an intramolecular 2 1 complex. When one boronic acid binds a saccharide, its counterpart cannot participate in dimer formation and seeks a guest. 

Seyama, Y., Kalckar, H. M. Specific tritium labeling of uridine diphosphogalactose 4-epimerase by d-1-3H Galactose. Biochemistry 11, 36—39 (1972). 

Fig.8 Structure of UDP-Gal with labeling of the residues (G galactose, R ribose, U uracil) and torsion angles. Reprinted with permission from [69] (supporting information) 2004, American Chemical Society...

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