Quantitative radiochromatographic analysis of the major groups of carbohydrates in cultured animal cells

2-Sulfotrehalose, a novel osmolyte in haloalkaliphilic archaea

A novel 1-->1 alpha-linked glucose disaccharide with sulfate at C-2 of one of the glucose moieties, 1-(2-O-sulfo-alpha-D-glucopyranosyl)-alpha-D-glycopyranose, was found to be the major organic solute accumulated by a Natronococcus sp. and several Natronobacterium species. The concentration of this novel disaccharide, termed sulfotrehalose, increased with increasing concentrations of external NaCl, behavior consistent with its identity as an osmolyte. A variety of noncharged disaccharides (trehalose, sucrose, cellobiose, and maltose) were added to the growth medium to see if they could suppress synthesis and accumulation of sulfotrehalose. Sucrose was the most effective in suppressing biosynthesis and accumulation of sulfotrehalose, with levels as low as 0.1 mM being able to significantly replace the novel charged osmolyte. Other common osmolytes (glycine betaine, glutamate, and proline) were not accumulated or used for osmotic balance in place of the sulfotrehalose by the halophilic archaeons.

High-performance liquid chromatographic separation of hyaluronan and four proteoglycans produced by human bone cell cultures

Four proteoglycans and hyaluronan synthesized by cultured human bone cells were isolated using a two-step high-performance liquid chromatography system involving desalting and buffer exchange with a TSK-GEL HW 40(S) column followed by ion-exchange separation on a Nucleogen 4000-10 DEAE column. The desalting of 4 M guanidinium HCl extracts by a TSK-GEL HW 40(S) column equilibrated in a formamide:KH2PO4 buffer produces greater than 95% recoveries, enables quantitation of label incorporation and requires only 40 min to complete. The Nucleogen 4000-10 DEAE column utilizes the same buffer system and requires only 100 min for the resolution of four distinct types of proteoglycans. The formamide:KH2PO4 buffer system is compatible with a previously developed polyacrylamide gel system for the electrophoretic profiling of proteoglycans. After separation by charge density, proteoglycans were further resolved by size distribution using a calibrated TSK-GEL HW 75(F) column which also enabled the estimation of the apparent Mr of hyaluronan produced by the bone cells. The same TSK-GEL HW 40(S) resin is used to exchange pooled proteoglycans into buffers for analyzing enzyme digests of glycosaminoglycan chains and core proteins. The technique has been applied to the analysis of biosynthetically labeled proteoglycans produced in culture by fetal and adult human bone cells. A distinct pattern of proteoglycan size and secretion for both cell types could be shown using this method. The method of analysis is useful for high yield and rapid screening of various cell types for both biosynthetic rate studies and analysis of patterns of proteoglycan synthesis.

Effect of cycloheximide and dexamethasone phosphate on hyaluronic acid synthesis and secretion in cultured human skin fibroblasts

We have studied some aspects of the regulation of hyaluronic acid synthesis in cultured human skin fibroblasts derived from normal individuals. In these cells 85% of radiolabeled glucosamine is incorporated into two types of macromolecules, hyaluronic acid and glycoproteins, characterized by district partitions between the cell and medium compartments. Treatment of cells with cycloheximide under conditions in which protein and glycoprotein synthesis is inhibited by at least 90% has no effect on hyaluronic acid synthesis. This result is consistent with the hypothesis that protein synthesis is not necessary for the synthesis of hyaluronic acid. Conversely, 5 X 10(-6) M dexamethasone phosphate inhibits hyaluronic acid by 60% but has no effect on protein or glycoprotein or glycoprotein synthesis. Concomitant treatment with dexamethasone phosphate and cycloheximide restores the synthesis of hyaluronic acid to normal values. The dexamethasone phosphate effect on hyaluronic acid synthesis is therefore not a primary induction response since it requires protein synthesis. The secretion of hyaluronic acid and glycoproteins from the cells into the medium is not affected by either of the two drugs. This experimental approach will be useful in the study of the regulation of glycosaminoglycan metabolism in human cells especially with respect to disorders of connective tissue.

The acid lability of the glycosidic bonds of L-iduronic acid residues in glycosaminoglycans

Heparan sulphate, heparin and dermatan sulphate were hydrolysed in 0.5M-H2SO4 at 100 degrees C. At intervals portions of the hydrolysate were removed and treated with HNO2 at pH 4.0 to cleave the glycosidic bonds of the N-unsubstituted hexosamine residues and to convert both free and combined hexosamines into anhydrohexoses. These hydrolysis/deamination mixtures were reduced with NaB3H4 and analysed by radiochromatography for alpha-L-iduronosylanhydrohexose, beta-D-glucuronosylanhydrohexose, and the free uronic acids and anhydrohexose. These data gave a kinetic profile of the cleavage of the alpha-L-iduronosyl and the beta-D-glucuronosyl bonds in these glycosaminoglycans. The beta-D-glucuronosyl bonds showed the expected resistance to acid hydrolysis, but the alpha-L-iduronosyl bonds were found to be as labile to acid as some neutral sugar glycosides. This unusual lability of alpha-D-iduronosyl-anhydromannitol and beta-D-glucuronosylanhydromannitol. The procedures used to follow the kinetics of glycosaminoglycan hydrolysis can also be sued to obtain quantitative analyses of L-iduronic acid, D-glucuronic acid and hexosamine in these polymers.