Chondroitin 6-sulfate, biosynthesis

Crocker sarcoma and Mecca lymphosarcoma tumors were found to accumulate the radioselenium slowly and continuously in contrast to rapid uptake and clearance of the label from most normal organs. Clinically, the affinity of tumors for selenium has been the basis for utilizing a radioactive nuclide of selenium as a tumor localizing agent (62, 64) The reason for the localization of selenium is not readily apparent but may reflect enhanced division rates, protein and chondroitin sulfate biosynthesis, or a decrease in the detoxification of selenium. An outgrowth of these observations has been to examine the in vitro effects of selenium supplementation on cellular propagation. 

Pedersen LC, Tsuchida K, Kitagawa H, Sugahara K, Darden TA, Negishi M. Heparan/chondroitin sulfate biosynthesis. Structure and mechanism of human glucuronyltransferase I. J. Biol. Chem. 2000 275 34580-34585. 

The dermis contains several types of cells, including fibroblasts, fat cells, macrophages, histiocytes, mast cells, and cells associated with the blood vessels and nerves of the skin. The predominant cell is the fibroblast, which is associated with biosynthesis of the fibrous proteins and ground substances such as hyaluronic acid, chondroitin sulfates, and mucopolysaccharides. 

Enzymic transfer of D-xylose from uridine 5 -(D-xylopyranosyI-HC pyrophosphate) to L-serine residues of endogenous protein acceptors from (a) a cell tumor of the mouse188 and (b) chick-embryo cartilage189 occurs in cell-free extracts of both of these tissues, in the absence of biosynthesis of protein. The enzyme preparations employed were from the supernatant liquor, although activity was also present in the insoluble fractions. In these two types of tissue, the acceptors are heparin and chondroitin sulfate, respectively, but the presence of other D-xylose-containing glycoproteins in ascites fluid from... 

It comes as no great surprise that trace elements may affect the growth and development of bone. Trace element deficiences profoundly alter hone metabolism in animals either directly or indirectly (3). The absence of a trace element in the diet can lead to inefficient functioning of a specific enzyme or enzymes that require the transition element as a cofactor. An example of this is the role of Cu and iron (Fe) in the cross-linking of collagen and elastins (4-9). The participation of Mn in the biosynthesis of mucopolysaccharides (10-12) is another example. Zn deficiency causes a reduction in osteoblastic activity, collagen and chondroitin sulfate synthesis and alkaline phosphatase activity (13-16). 

The initial stages of chondroitin and heparan sulfate biosynthesis. Each enzyme is defined by its shorthand name(s) as well as by the abbreviations of the relevant known or proposed corresponding Drosophila and Caenorhabditis genes... 

Various studies (Jll) of the incorporation of D-[6- C] ucose, L-[i C]lysine, and [ °S]sulfate into the chondroitin sulfate proteoglycan of chick embryonic cartilage show that the carbohydrate and protein moieties are synthesized at different relative rates. Furdier approaches to the order of biosynthesis of the proteoglycan moieties have been made (e.g., B17, M13, M16, 06 see also Section 5, p. 36) by a comparison of their rates of formation in the presence of a specific inhibitor of the biosynthesis of one of them, and all the observations accord with protein synthesis preceding polysaccharide elaboration. 

Examples of the use of induced biosynthetic effects for the deduction of the processes involved include the use of puromycin and cyclohexi-mide. These compounds, according to experiments with other systems, inhibit protein synthesis. Thus the inhibition of biosynthesis of hyaluronic acid and dermatan sulfate in human fibroblast cultures (M13, M16), of hyaluronic acid in synovial cells (S31), and of chondroitin sulfate (HI) led to the conclusion that the synthesis of protein acceptor is necessary for the polysaccharide chain initiation. Comparison of the effects of 1-butanol on the biosynthesis of chick cartilage chondroitin sulfate and streptococcal hyaluronic acid led to the suggestion that binding of Mg + ions and the uridine diphosphate moiety results in stabilization of the spatial arrangement of the specific enzymes (S47, T4). 

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