Frank C. Happold

Studies on adenosine-5′-phosphosulphate reductase from Thiobacillus denitrificans

Summary A procedure for the purification of adenosine-5′-phosphosulphate reductase from cell-free extracts of Thiobacillus denitrificans is presented. The purified enzyme was shown to contain FAD and ferric iron. The nucleotide specificity of the enzyme was investigated and K m values for AMP, GMP and sulphite are given. The effect of various inhibitors on the activity of the adenosine-5′-phosphosulphate reductase was studied and it was concluded that the enzymic activity was not dependent on sulf-hydryl groups.

The bacterial formation of acetylmethyl-carbinol and 2:3-butylene glycol

The formation of acetylmethyccarbinol and 2:3-butylene glycol has been studied using washed cell suspensions of Aerobacter aerogenes. The results show marked differences in the production of the two four-carbon compounds from glucose and pyruvic acid and make it improbable that a simple decarboxylation of pyruvic acid to acetaldehyde followed by condensation occurs. The results with mixed glucose-pyruvic acid substrates suggest that the formation of acetylmethylcarbinol from pyruvic acid may be associated with a reaction of the glycolytic cycle. The effects of hydrogen donors on pyruvate dissimilations support the hypothesis that this association may take the form of a linked oxidation-reduction reaction. The implication of these findings on the problem of the mechanism of acetylmethylcarbinol and 2:3-butylene glycol formation is discussed.

The enzymic formation of acetylmethylcarbinol and related compounds

A cell-free enzyme extract which catalyses the anaerobic decarboxylation of pyruvic acid with the formation of acetylmethylcarbinol has been isolated from Aerobacter aerogenes by three methods (viz. by grinding with powdered glass, by shaking with glass beads and by extraction of an acetone dried preparation). Adsorption of the complex, fractionation studies and an examination of the effects of coenzyme factors indicate that at least two systems are involved. The whole system is able to condense acetate but not acetaldehyde during the concurrent decarboxylation of pyruvate. It is suggested that acetate may be involved in one type of enzymic synthesis of acetylmethylcarbinol and that acetaldehyde is condensed only after oxidation to acetate. The possibility of the occurence of diacetyl as an intermediate in the reaction involving acetate is discussed.

Quinanil as a Bactericidal Agent in the Isolation of an Insect Flagellate.

A flagellate from Polietes lardaria , closely allied to Herpetomonas muscarum , has been repeatedly isolated in bacteria-free culture by the use of quinanil after numerous attempts to isolate it by other methods with one exception had failed. The flagellates were exposed to 1/10,000 or 1/100,000 quinanil for 2–4 or more hours and cultivated in Locke serum agar, the medium for the first subculture containing quinanil in concentrations of 1/10,000 or 1/50,000. The proofs of the purity of the cultures were exhaustive. We are greatly indebted to Dr St John-Brooks and the National Collection of Type Cultures for certain of the flagellates isolated by Noguchi and Tilden. One of us (F. C. H.) has also been in receipt of grants from the Medical Research Council, and he would like to take this opportunity of expressing his thanks to that body.