Minerals cofactors

Calcium functions at both extracellular and cellular sites. Its extracellular functions consist of the maintenance of normal ion products for mineralization cofactor for prothrombin factors Vll, IX, and X and maintenance of plasma membrane stability and permeability. 

The last column in the table lists some of the functions of minerals. It should be noted that almost all of the macroelements in the body function either as nutrients or electrolytes. Iodine (as a result of its incorporation into iodothyronines) and calcium act as signaling substances. Most trace elements are cofactors for proteins, especially for enzymes. Particularly important in quantitative terms are the iron proteins hemoglobin, myoglobin, and the cytochromes (see p. 286), as well as more than 300 different zinc proteins. 

Mecfianism of Action A mineral that acts as a cofactor for enzymes that are important for protein and carbohydrate metabolism. Therapeutic Effect Zinc oxide acts as a mild astringent and skin protectant. Zinc sulfate helps maintain normal growth and tissue repair as well as skin hydration. 

Water accounts for over half the body mass (55%) of the average human. Of the remaining 45%, 19% is protein, 19% is lipid, less than 1% is carbohydrate, and 7% is inorganic material. Nutrients must contain the raw materials that go into the construction of the components of the human body. In addition, nutrients must supply the necessary chemical energy and enzyme cofactors (vitamins and trace metal elements) that are required for the maintenance and growth of the human body. The human body requires nutrients such as water, amino acids, fats, carbohydrates, and major minerals in large amounts. Vitamins and trace metal elements are required in smaller amounts. 

An enzyme cofactor can be either an inorganic ion (usually a metal cation) or a small organic molecule called a coenzyme. In fact, the requirement of many enzymes for metal-ion cofactors is the main reason behind our dietary need for trace minerals. Iron, zinc, copper, manganese, molybdenum, cobalt, nickel, and selenium are all essential trace elements that function as enzyme cofactors. A large number of different organic molecules also serve as coenzymes. Often, although not always, the coenzyme is a vitamin. Thiamine (vitamin Bj), for example, is a coenzyme required in the metabolism of carbohydrates. 

Phase II Reactions. As with phase I reactions, phase II reactions usually depend on several enzymes with different cofactors and different prosthetic groups and, frequently, different endogenous cosubstrates. All of these many components can depend on nutritional requirements, including vitamins, minerals, amino acids, and others. Mercapturic acid formation can be cited to illustrate the principles involved. The formation of mercapturic acids starts with the formation of glutathione conjugates, reactions catalyzed by the glutathione -transferases. 

Some non-enzymatic antioxidants play a key role in these defense mechanisms. These are often vitamins (A, C, E, K), minerals (zinc, selenium), caretenoids, organosulfur compounds, allyl sulfide, indoles, antioxidant cofactors (coenzyme Qio)> and polyphenols (flavonoids and phenolic acids) [1,37]. Further, there is good evidence that bilirubin and uric acid can act as antioxidants to help neutralize certain free radicals [38]. Alpha-carotene, lycopene, lutein, and zeaxanthine [39] can be considered subgroups of carotenoids [40] that are effective antioxidant compounds. 

Vitamins are required in the diet for groMh, maintenance, and reproduction. These qualities are shared by other nutrients, such as the amino adds and the minerals- Why are amino acids and minerals not called vitamins The vitamins share a family of characteristics. They are organic compounds required in the diet in only smaii amounts They are not catabolized to satisfy part of the energy requirement and are not used for structural purposes. Many vitamins are used as cofactors for enzymes. Pyruvate dehydrogenase is one striking example. This enzj me uses five cofactors, where four of these cofactors are derived from vitamins-... 

As we have seen, trace metals are involved as cofactors of metalloenzymes and proteins, in all general metabolic processes of phytoplankton, including photosynthesis and respiration, and in assimilation of macronutrients. The vertical profiles of trace metal concentrations in open oceans (Figure 10.9) are like those of macronutrients that is, they show surface depletion resulting from algal uptake and partial release at greater depth due to mineralization. 

In addition to providing energy, dietary components also produce precursors for the synthesis of structural compounds and supply the essential fatty acids and amino acids (which the body cannot synthesize) and the vitamins and minerals (which often serve as cofactors for enzymes). 

Cofactors, many of which are minerals or compounds produced from vitamins, aid the enzymes that catalyze these metabolic reactions. 

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