Vitamins metabolic interrelationships

There are several metabolic interrelationships between riboflavin and vitamin Bg. The conversion of pyridoxine or pyridoxamine phosphates to pyri-doxal phosphate is catalyzed by a flavoenzyme (pyri-doxaminephosphate oxidase EC 1.4.3.5), so that a deficiency of riboflavin may, at certain key sites, result in a secondary deficiency in Bg-dependent pathways. More evidence is needed to clarify the extent and importance of these interactions. 

R. S. Flueck, J. A. "The Interrelationships Between Vitamin D and Parathyroid Hormone in Disorders of Mineral Metabolism in Man" (Proceedings of 2nd Vitamin D Symposium), Weisbaden, West Germany, Oct., 1974, In Press. 

In 1942 it was shown that the urine of pyridoxine-deficient rats contained large amounts of xanthurenic acid (L2). This was the starting point for studies on the interrelationship among vitamin Be, tryptophan, and protein metabolism. 

Eastell R, Yergey AL, Vierira NE, Cedel SL, Kumar R, Riggs BL. Interrelationship among vitamin D metabolism, true calcium absorption, parathyroid function, and age in women evidence of an age-related intestinal resistance to 1,25-dEiydroxyvitamin D action. J Bone Miner Res 1991 6 125-32. 

FIGURE 53-6 Interrelationships and metabolic roles of vitamin and folic acid. See text for explanation and Figure 53-9 for structures of the various folate coenzymes. FIGLU, formiminoglutamic acid, which arises from die catabolism of histidine Tell, transcobalamin II CH3H4PteGlUj, mediyltetrahydrofolate. 

FIG. 1. Interrelationships between vitamin B6 and phosphorylase metabolism. The low rate of turnover of glycogen phosphorylase (gpb) and the lack of exchange of free and protein-bound PLP mean that exchange into the muscle pool is largely controlled by the kinetics of turnover of the enzyme. At present, it is not known whether resolution of the holo-enzyme is a prerequisite or consequence of phosphorylase degradation. Reproduced with permission of llie Biochemical Journal. 

Luhby, A., Cooperman, J. Folic acid deficiency in man and its interrelationship with vitamin B12 metabolism. Advanc. Metab. Disord. 1, 263-334(1964)... 

Zinc represents another nutrient whose nutritional status may influence plasma vitamin A and RBP levels in malnourished children. Interrelationships between zinc and vitamin A have been reviewed in detail by Solomons and Russell (1980) and by Smith (1980), and are discussed and summarized in Chapter 6, Vol. 1. Studies in experimental animals have shown that zinc deficiency is associated with low plasma vitamin A and RBP levels. It has been suggested that this may be due in part to impaired hepatic synthesis of RBP (Smith et al., 1974). This effect on RBP production has not been thought to be in any way specific for RBP rather hepatic synthesis of plasma proteins in general appears to be impaired in zinc deficiency, with RBP being one of the hepatic proteins most sensitive to this deficiency. The main effect of zinc deficiency on vitamin A and RBP metabolism appears, however, to be secondary to the depressed food intake... 

INTERRELATIONSHIPS. Copper, along with certain vitamins, is involved in iron metabolism. 

Absorption, Metabolism, Excretion Factors Which May Affect Dietary Selenium Functions of Selenium Interrelationship of Selenium and Vitamin E Deficiency Symptoms Evidence of Selenium Deficiencies Associations Between Certain Diseases and Selenium... 

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