Manganese enzymes activated

Manganese acts as a cofactor of mevalonate kinase and farnesyl pyrophosphate synthetase. Mevalonate kinase and possibly one other manganese-activated enzyme are necessary for the formation of mevalonate from acetate (3). Farnesyl pyrophosphate synthetase acts to add one 5-carbon unit to geranyl pyrophosphate to make farnesyl pyrophosphate (4) (Figure 1). 

Manganese-activated enzyme an enzyme that does not bind Mn tightly, but for which the enzymatic activity is nevertheless enhanced by addition of Mn. Manganese may or may not be the cation bound in vivo... 

In contrast to manganese-activated enzymes, manganoen-zymes contain tightly bound Mn and it is often quite difficult to remove the Mn from the protein. The activity of manga-noenzymes is not enhanced by the addition of free Mn to the assay medium. Both classes of proteins are discussed since the distinction involves only the relative strength of the Mn-protein interaction and not any fundamental properties of the Mn active site. 

Experiments done on isolated chloroplasts showed that all the chloroplast reactions tested are inhibited by copper and that manganese reduced this effect96. The lack of influence of light in these experiments implies that the photoact per se is not involved. The authors suggested that a manganese activated enzyme was involved. Another possible mechanism is that copper and manganese both influence membrane permeability, but in opposite directions. 

Further reading covering the general chemistry and structures of manganese metalloproteins and manganese-activated enzymes can be obtained in the reviews of McEuen [83], Wieghaidt [84], and Vincent and Christou [85]. 

In contrast to the relatively few manganese metalloenzymes, there are a large number of manganese-activated enzymes, including hydrolases, kinases, decarboxylases, and transferases. 

Manganese ions enzyme activators, 6,578 probes, 6,563 RNA polymerases activation, 6, 585 transport microbes, 6, 569 plants, 6, 572 Manganese oxide colloidal... 

Catalases catalyze the conversion of hydrogen peroxide to dioxygen and water. Two families of catalases are known, one having a heme cofactor and the second a structurally distinct family, found in thermophilic and lactic acid bacteria. The manganese enzymes contain a binuclear active site and the functional form of the enzyme cycles between the (Mn )2 and the (Mn )2 oxidation states. When isolated, the enzyme is in a mixture of oxidation states including the Mn /Mn superoxidized state and this form of the enzyme has been extensively studied using XAS, UV-visible, EPR, and ESEEM spectroscopies. Multifrequency EPR and microwave polarization studies of the (Mn )2 catalytically active enzyme from L. plantarum have also been reported. ... 

Manganese is essential for the synthesis of chondroitin sulfate, a mucopolysaccharide which is an important component of bone cartilage. Manganese is also required to activate enzymes involved in the synthesis of polysaccharides and... 

Manganese The human body is estimated to contain a total of 10-20 mg Mn. The RDA is between 2 and 5 mg per day. Manganese is involved in many enzymatic processes as a metalloenzyme or as a cofactor. In contrast to the Mn-activated enzymes, there are few Mn metalloenzymes (arginase, pyruvate carboxilase, and Mn-superoxide dismutase) [14]. The content of Mn in milk responds rapidly to changes in dietary intakes of this metal. 

Manganese is a constituent of many important metalloen-zymes and also acts as a nonspecific enzyme activator. Mn " ions can be replaced by Mg, Co % and other cations during the activation of some enzymes. Some important manganese-dependent enzymes are discussed below. 

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