Soluble DGlucose Dehydrogenase sGDH

D-Glucose ^ D-glucono-8-lactone

As mentioned above, A. calcoaceticus contains s-GDH in addition to m-GDH. s-GDH purified from the soluble fraction of A. calcoaceticus does not cross-react with the antibody for m-GDH [38]. Subsequently, s-GDH and m-GDH were purified separately from A. calcoaceticus and shown to be distinctive in all aspects including optimum pH, kinetics, substrate specificity, ubiquinone reactivity, molecular size, and immunoreactivity [39].

s-GDH of A. calcoaceticus is a monomer consisting of a single polypeptide of 48-55 kDa containing one PQQ molecule. A gene (gdhB) for the enzyme has been cloned and the gene product is estimated to be a polypeptide of 52.8 kDa that contains a 24-amino-acid signal sequence at its N-terminus and thus it is expected to become the mature protein of 50.2 kDa having no hydrophobic regions. Thus, s-GDH seems to be translocated through the cytoplasmic membrane into the periplasmic space.

s-GDH is capable of catalyzing the oxidation of disaccharides, lactose, or maltose, as well as D-glucose. The enzyme is able to donate electrons to several artificial dyes, including PMS, DCIP as well as short-chain ubiquinone homologs, Qj and Q2, but it is unable to react with the longer chain ubiquinones Q6 and Q9 [39]. s-GDH was purified from the soluble fraction of A. calcoaceticus with the overall recovery of 28% and showed a final specific activity of 2210 units mg-1. The substrate specificity of s-GDH is different from that of m-GDH. s-GDH oxidizes D-glucose (100%), D-fucose (28%), D-xylose (15%), D-galactose (30%), maltose (93%), and lactose (72%), while m-GDH is less reactive with disaccharides: D-glucose (100%), D-fucose (119%), D-xylose (81%), D-galactose (73%), D-ribose (54%), maltose (13%), and lactose (5%).

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Heal Yourself With Qi Gong

Qigong also spelled Ch'i Kung is a potent system of healing and energy medicine from China. It's the art and science of utilizing breathing methods, gentle movement, and meditation to clean, fortify, and circulate the life energy qi.

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