PubMed · 4264352
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S A Plotkin. 1972. Antibiotics, 1972.. https://doi.org/10.1177/000992287201101205
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Lactosaminated N-succinyl-chitosan (Lac-Suc) was prepared by reductive amination of N-succinyl-chitosan (Suc) and lactose using sodium cyanoborohydride. Six-day reaction using lactose (12.8-fold (w/w)) yielded Lac-Suc with lactosamination degree of 30% (mol/sugar unit). Fluorescein thiocarbamyl-Lac-Suc (Lac-Suc-FTC) was prepared by labeling Lac-Suc with fluorescein isothiocyanate. Lac-Suc-FTC was injected intravenously at a dose of either 1 (high dose) or 0.2 (low dose) mg/mouse. At both doses, Lac-Suc-FTC initially underwent fast hepatic clearance, showed maximum liver localization at 8 h, and the amounts localized there were maintained even at 48 h post-injection. Very slow excretion into feces and urine was observed. The ratio of liver AUC(0--48 h) to plasma AUC(0--48 h) at low dose was three times higher than that at high dose. On the other hand, the Suc derivative, Gal-Suc, obtained by reductive amination of Suc/galactose showed very little distribution to the liver similarly to Suc itself. Further, since the liver uptake of Lac-Suc-FTC was inhibited by asialofetuin, it was suggested that the liver distribution of Lac-Suc should be concerned with asialoglycoprotein receptor. Thus, Lac-Suc was found available as a carrier exhibiting a high affinity to and long retention in the liver.
1H NMR spectroscopy has been used to investigate the transfer of sialic acid from sialic acid donor molecules to acceptor molecules using the trans-sialidase from Typanosoma cruzi. It is clearly demonstrated that NMR spectroscopy is an efficient and powerful means of monitoring the trans-sialidase promoted transfer of sialic acid from donor to acceptor.
Although there are numerous methods available to hydrolyze glycans utilizing strong acids, it all requires lengthy steps to obtain quantitative yield. We have developed a new simple one-step method for analysis of amino and neutral monosaccharides of glycoproteins quantitatively. Free monosaccharides were found to be stable during hydrolysis of glycans with 6 N HCI at 80 degrees C up to 2 h. Using this condition, analysis of free monosaccharides hydrolyzed from the bovine fetuin showed sugar composition of Gal: Man: GlcN: GaIN = 13.2: 11.0: 15.5: 2.6, which is closely matched with the reported value of 12.4: 9.6: 17.2: 2.7 (Townsend et al., ABRF News 8: 14, 1997). This method was shown to be applicable to varieties of well-characterized glycoproteins, erythropoietin, fibrinogen and soybean agglutinin. The amounts of sugars released under the condition were very close to the experimental values by other procedures or to the theoretical ones. This condition was found to be suitable for direct sugar analysis of fetuin, which have been immobilized onto polyvinylidene difluoride membrane. Based on these results, it support that the 6 N HCl/80 degrees C/2 h is the simplest method for quantitative analysis of monosaccharide composition of glycoproteins.