AHyd roxylation

Several Streptomyces roseochromogenes strains are effective in microbial 16a-hydroxylation biotransformations that yield the highly active glucocorticoids triamcinolone and its 6a-fluoro derivative fluocinolone [44-46]; however, the 2P-hydroxylating capacity ofthe known strains leads to undesired byproducts [47]. The isolate Streptomyces roseochromogenes NCIB 10984 was shown to contain a cytochrome P450 which, in conjunction with two indigenous electron transfer proteins (roseoredoxin and roseoredoxin reductase) hydroxylates exogenous progesterone firstly to 16a-hydroxyprogesterone, whereupon a second phase bioconversion to 2p,16a-dihydroxyprogesterone takes place [48]. Interestingly, the relative amount of the two products seems to be modulated by posttranslational modification of the roseoredoxin [49]. A reconstituted incubation containing the three purified proteins and NADH, the natural electron donor, produced identical hydroxyprogester-one metabolites as is observed in intact cells. Peroxy and hydroperoxy compounds act in a shortened form of the cycle known as the "peroxide shunt" by replacing the natural pathway requirement for the electron donor NADH, the electron transfer proteins, and molecular O2, the terminal electron acceptor.

In an NaIO4-supported incubation, the initial rate of progesterone hydroxylation was marginally higher (1.62 mmol progesterone per mmol P450 h-1) than in the reconstituted natural incubation (1.18 mmol progesterone/mmol P-450/h) but the product yield was significantly lower, 0.45 mol hydroxyprogesterone produced per mol P450 compared with 6.0 mol hydroxyprogesterone produced per mol P450. From these data the authors concluded that in the reconstituted natural pathway, progesterone 16a-hydroxylase P450 supports multiple rounds of hydroxylation in contrast to a likely single oxygenation by a minority of P450s in the peroxide shunt pathway.

Heal Yourself With Qi Gong

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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