Mucopolysaccharide metabolism, enzymes

The effect of manganese deficiency or excess on carbohydrate homeostasis have been studied by Keen, Hmley and coworkers, with some focus on pyruvate carboxylase and PEP carboxykinase [302-304]. Other evidence indicates that Mn(II) has an insulin-mimetic effect, acting to stimulate protein kinases or phosphatases that control enzymes involved in glycolysis, gluconeogenesis, or the hexose mono-P pathway [305-307]. A key role of Mn(II) in mucopolysaccharide metabolism has long been recognized [6]. 

Metabolic Functions. Manganese is essential for normal body stmcture, reproduction, normal functioning of the central nervous system, and activation of numerous enzymes (126). Synthesis of the mucopolysaccharide chondroitin sulfate involves a series of reactions where manganese is required in at least five steps (127). These reactions are responsible for formation of polysaccharides and linkage between the polysaccharide and proteins that form... 

Manganese 1 8 2.5-5 mg Enzymes in protein and energy metabolism, superoxide dismutase, mucopolysaccharides synthesis Unknown Toxicity by inhalation... 

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 chondroitin sulfate-protein complex in rat costal cartilage is metabolized as a single unit (G9). Subcutaneous injection of a mixture of DL-lysine-C and Na2S 04 resulted in labeling of both mucopolysaccharide and protein moieties. Since no differences in the rates of turnover of these moieties were apparent, it seems that the entire complex is synthesized as a unit and then extruded into the matrix. The suggestion (G9) that chondroitin sulfate may be released from cartilage in vivo by the action of proteolytic enzymes is not without support (T3). 

Fetal pig epidermis contains hyaluronic acid and chondroitin 4-sulfate containing mucopolysaccharide (S15) as does human epidermis (M13), and some of the enzymes of uronic acid metabolism are present in human epidermis (F24). Also Barker et al. (B6) have shown uptake of radioactive sulfate into epidermis, and Braun-Falco et al. (B33) have shown that psoriatic epidermis is more active than normal epidermis in accumulating radioactive sulfate in vitro. There is also a suggestion that methionine sulfur may be preferentially accumulated in psoriatic lesions (B26, L6). There seems to be little doubt, therefore, that mucopolysaccharides are formed, and there is some suggestion that they may be formed in greater amounts in psoriatic skin lesions. The next section will consider the possibility that they are of importance in the cell membrane and intercellular contact. 

In industry, manganese is a metallic element used chiefly as an alloy in steel to give it toughness. In nutrition, it is an essential element for many animal species. Manganese is an activator of several enzyme systems involved in protein and energy metabolism and in the formation of mucopolysaccharides. The human body contains 12 to 20 mg of manganese. So, an essential function of the element must be assumed to exist in man. 

Peroxisomes are more recently recognized intracellular structures that contain catalase, D-amino acid oxidase, and urate oxidase (Masters and Holmes, 1977). The cytoplasm contains some or all of the enzymes of the glycolytic, pentose phosphate, galactose, uronic acid, glycogen, fructose, mucopolysaccharide, pyrimidine, purine, amino acid, fatty acid biosynthetic, and other metabolic pathways. 

Manganese is involved in carbohydrate, lipid and protein metabolism and is required for the synthesis of glycoproteins and mucopolysaccharides such as hyaluronic add. It is also involved in glucose metabolism. In plants, it is involved in the enzyme that splits water into oxygen and hydrogen. 

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