Manganese binding

Figure 31 Schematic view of the manganese binding in arginase.

Mester T, Tien M (2001) Engineering of a manganese-binding site in lignin peroxidase isozyme H8 from Phanerochaete chrysosporium. Biochem Biophys Res Commun 284 723-728... 

Wilcox, S. K., Putnam, C. D., Sastry, M., Blankenship, J., Chazin, W. J., McRee, D. E., and Goodin, D. B., 1998, Rational design of a functional metalloenzyme introduction of a site for manganese binding and oxidation into a heme peroxidase, Biochemistry 37 16853nl6862. 

R Mei, JP Green, RT Sayre and W Frasch (1989) Manganese binding proteins of the oxygen-evoiving compiex. Biochemistry 28 5560-5567... 

Metal analysis showed that manganese-substituted carbonic anhydrase contained up to 80 mol% manganese and 5-10 mol% zinc. The remaining 10-15 mol% was likely apo-carbonic anhydrase since manganese binds to apo-carbonic anhydrase less tightly than zinc (pA p =< 3.4-4.0 for Mn(ll) vs. 12.0 for Zn(ll)) [39] and dissociates rapidly in the presence of zinc = 27 min at pH 6.8) [35]. The samples showed 10-15% of original hydrolytic activity toward p-nitrophenyl acetate, likely due both to the remaining zinc and to hydrolytic activity of CA[Mn], which is 7-8% of the native carbonic anhydrase [40]. 

Manganese-binding centers were first revealed in thylakoid membranes by EPR methods, and it is now understood that four manganese ions are necessary for oxygen evolution during water photo-oxidation. Plastoquinone (PQ) acts as a transmembrane carrier of electrons and protons between reaction centers of two photosystems in the case of noncyclic electron transfer and may also serve as a molecular tumbler that switches between one-electron reactions and two-electron reactions. Pheophytin is an intermediate acceptor in PS II. Direct formation of P680 pheophytin ion radical pairs was revealed by experiments on magnetic interactions between pheophytin and PQ reflected in the EPR spectra. 

MANGANESE-BINDING SITE OF PHOTOSYSTEM H REACTION CENTER. 

One method to investigate the role of the 33 kDa protein in manganese binding and determine its binding site in PS II involves the substitution of amino acids by site directed mutagenesis of cDNA. This would require an expression system for the 33 kDa protein and its mutants. Here we present the functional expression of the 33 kDa protein from spinach in E,coli. 

Manganese-Binding Site of Photosystem II Reaction Center 757... 

Likewise, a bacterium named Citrobacter freundii has an essential enzyme that moves phosphate from ATP to something else. If manganese binds in magnesium s place, the enzyme changes to form two bonds to the same phosphate, making a little phosphate circle. If the bacterium needs to make phosphate circles, it just ships in a little manganese and an old enzyme performs new chemistry. 

Manikandan P, Carmieli R, Shane T, Kalb AJ, Goldfarb D. 2000. W-band ENDOR investigation of the manganese-binding site of concanavalin A determination of proton hyperfine couplings and their signs. JAm Chem Soc 122 3488-3494. 

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