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PubMed1983

Antitumor activity of tetrahydro-2-furanyl- and tetrahydro-2-pyranyl-glucans obtained by chemical modification of (1 leads to 3)-beta-D-glucan from Alcaligenes faecalis var. myxogenes IFO 13140 and its lower molecular weight glucans.

The well-defined (1 leads to 3)-beta-D-glucan with DP (degree of polymerization) 540 and the various chain-length (1 leads to 3)-beta-D-glucans prepared by its hydrolysis were chemically modified to furanyl- and pyranyl-derivatives. As a primary screening, the effect of 20 derivatives thus obtained was tested on Sarcoma 180 solid tumor transplanted sc into allogeneic ICR mice; the dose was 10 mg/kg ip for 10 days. Eleven derivatives that showed a strong antitumor effect on Sarcoma 180 were also tested on Meth-A solid tumor in syngeneic mice. Of the derivatives tested, five furanyl-derivatives (F-4, F-6, F-7, F-10, and F-11) and one pyranyl-derivative (P-5) had potent antitumor effects on this syngeneic tumor system at ip doses of 10 or 30 mg/kg for 10 days. By oral administration, only two derivatives (F-10 and P-3) showed moderate antitumor activity against Sarcoma 180, without complete tumor regression. The mechanism of action of these derivatives was considered to be host-mediated and similar to that of the original glucan, because of a lack of effect in vitro.

Alcaligenes↗
PubMed1980

[Reversible oxidation-reduction of NAD by hydrogen, catalyzed by soluble hydrogenase from Alcaligenes eutrophus Z-1].

The kinetics of NAD reduction by hydrogen, catalyzed by soluble hydrogenase from the hydrogen bacterium A. eutrophus Z-1 within a wide range of NAD substrate concentrations and pH were studied under aerobic and anaerobic conditions. The autocatalytic type of the reaction (with an induction period) and positive kinetic cooperativity with respect to NAD substrate at pH values greater than 8.0 were observed. A steady hydrogen release in a two-enzyme system involving hydrogenase, formiate dehydrogenase, formiate and NAD was demonstrated. A multistep pattern of the reaction mechanism of NAD reduction allowing to explain the autocatalytic type of NAD reduction by hydrogen as well as insensitivity of the reaction to air oxygen were proposed. Possible types of regulation of the soluble hydrogenase activity in the cell are discussed.

Aerobiosis↗