Galactosylation

Ricin (toxin from Castor bean Ricinus communis) [A chain 96638-28-7 B chain 96638-29-8] Mr -60,000, amorphous. Crude ricin, obtained by aqueous extraction and (NH4)2S04 pptn, was chromatographed on a galactosyl-Sepharose column with sequential elution of pure ricin. The second peak was due to ricin agglutinin. [Simmons and Russell Anal Biochem 146 206 1985.) Inhibitor of protein synthesis. EXTREMELY DANGEROUS, USE EXTREME CARE [instructions accompany product]. 

FIGURE 6.20 A disaccharide of galactose and glucose is covalently linked to the 5-hydroxyl group of hydroxylysines in collagen by the combined action of the enzymes galactosyl transferase and glucosyl transferase. 

Alternatively, penta-O-acetyl-galactose can be converted to the known 2,3,4,6-tetra-O-acetylgalactopyranosyl azide59 which after treatment with sodium methoxide in methanol and subsequent pivaloylation with pivaloyl chloride in pyridine, also furnishes the O-pivaloylated galactosyl azide60. 

Although the (/ )-diastercomer is the minor component, as directly determined by HPLC it crystallizes from the solution of the diastereomeric mixture of the JV-galactosyl-tm-leucinonitriles63. 

The inducing urabinosyl matrix compound can be recovered after hydrolytic release of the enantionierically pure L-amino acid75,76. as indicated above, for the galactosyl derivatives of D-amino acids73,74. 

The highly branched GaM of Mimosa seeds, isolated by a scaled-up process [186] at a yield of 20% of seed weight, showed a Man Gal ratio of 1.1 1 and structural features of the gum obtained on a laboratory scale [ 183]. Based on C-NMR spectroscopy of GaM from Cassia angustifolia [179], with a Man Gal ratio of 2.9 1, a blockwise pattern of the galactosyl branches was suggested. 

The slightly galactosylated mannans are essentially linear polymers. As a result of their cellulose-like (1 4)-/3-D-mannan backbone, they tend towards self-association, insolubility, and crystallinity. Crystallographic study of C. spectabilis seed GaM [180] with a Man Gal ratio 2.65 1 suggested an orthorhombic unit cell with lattice constants of a = 9.12, b = 25.63, and c = 10.28 the dimension b was shown to be sensitive to the degree of galactose substitution and the hydration conditions [180 and references therein, [191]]. 

Galactosylated chitosan prepared from lactobionic acid and chitosan with l-ethyl-3-(3-dimethylaminopropyl)-carbodiimideand N-hydroxysuccinimide was a good extracellular matrix for hepatocyte attachment [155] (Fig. 4). Furthermore, graft copolymers of galactosylated chitosan with poly(ethylene glycol) or poly(vinyl pyrrolidone) were useful for hepatocyte-targeting DNA carrier [156,157]. 

Artificial glycopolymers having a-galactosyl epitope are of interest from the viewpoint of medical transplantation of pig liver since they can block im-... 

Figure 5.8 Electrospray and transformed electrospray spectra of the light- and heavy-chain antibody fragments of recombinant ritnximab obtained by LC-MS analysis. Reprinted from 7. Chromatogr., A, 913, Wan, H. Z., Kaneshiro, S., Frenz, J. and Cacia, J., Rapid method for monitoring galactosylation levels dnring recombinant antibody production by electrospray mass spectrometry with selective-ion monitoring , 437-446, Copyright (2001), with permission from Elsevier Science.

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