B. P. Sleeper

Bio: B. P. Sleeper is an academic researcher from University of California, Berkeley. The author has contributed to research in topics: Bacterial oxidation & Benzoates. The author has an hindex of 4, co-authored 4 publications receiving 132 citations.

The bacterial oxidation of aromatic compounds; III. The enzymatic oxidation of catechol and protocatechuic acid to beta-ketoadipic acid.

Abstract: Evans (1947) observed that cultures of Vibrio 01 developing at the expense of phenol gave an intense violet Rothera reaction during the later stages of growth. The Rothera test is a nitroprusside reaction used clinically to detect the presence of \"acetone bodies\" (acetone and acetoacetic acid) in urine. Although Evans did not succeed in identifying the substance responsible for the positive Rothera reaction in cultures of Vibrio 01, he established the fact that it was an organic acid that was considerably less ether-soluble than acetoacetic acid. Subsequently Kilby (1948) isolated the acid from culture filtrates of Vibrio 01 and identified it as ,3-ketoadipic acid, a 6-carbon dicarboxylic acid. He concluded that it was an intermediate in the oxidation of the benzene ring. As reported in an earlier paper (Sleeper, Tsuchida, and Stanier, 1950), we have succeeded in obtaining dried cell preparations of Pseudomonasfluorescens capable of oxidizing catechol and protocatechuic acid. The dried cell preparations were found to attack both substrates with a much lower oxygen uptake per mole than that which occurs during the equivalent oxidations by living cells, a fact which suggested that the oxidations by dried cells are blocked at an early stage. The investigations reported in the present paper show that both aromatic compounds are converted quantitatively by dried cells into ,B-ketoadipic acid, thus confirming in a direct manner Kilby's inference that this aliphatic acid is an intermediate in the oxidations of aromatic compounds.

The bacterial oxidation of aromatic compounds; the preparation of enzymatically active dried cells and the influence thereon of prior patterns of adaptation.

Abstract: Our evidence concerning the pathways for the oxidation of aromatic compounds by Pseudomonas fluorescens (Stanier, 1947, 1948; Sleeper and Stanier, 1950) has been accumulated almost entirely by use of the technique of simultaneous adaptation. Although we believe that the logical basis of this method is sound, the technique is necessarily an indirect one. Consequently it appeared desirable to confirm the reactions postulated by isolation and study of the various enzymes involved. The present paper is concerned with preliminary phases of this work: the techniques for preparing dried cells and the effect of pre-established adaptive patterns on enzymatic activity in vitro.

The bacterial oxidation of aromatic compounds. V. Metabolism of benzoic acids labeled with C14.

Abstract: There is good evidence (Stanier, 1950) that the bacterial oxidation of benzoic acid proceeds via catechol, but the biochemical mechanism of catechol formation is completely obscure at the present time. Since all likely aromatic intermediates, including phenol, the monohydroxybenzoic acids, 2,3and 3 ,4-dihydroxybenzoic acid, and salicylaldehyde have been excluded either on the basis of unutilizability or through the analysis of adaptive patterns (Sleeper and Stanier, 1950), it seems probable that the conversion is accompanied by a temporary partial dearomatization of the benzene ring. Unfortunately, the enzyme system catalyzing the reaction is inactivated during the preparation of dried cells (Sleeper, Tsuchida, and Stanier, 1950), and hence the problem cannot yet be investigated on the enzymatic level. It appeared possible, however, that some additional information about the process could be obtained from an analysis of the metabolism of specifically-labeled benzoic acids by intact cells, which was accordingly undertaken. During the course of this work the ultimate metabolic fate of two of the carbon atoms in benzoic acid was also determined.

Synthesis of the Enzymes of the Mandelate Pathway by Pseudomonas putida I. Synthesis of Enzymes by the Wild Type

Abstract: Hegeman, G. D. (University of California, Berkeley). Synthesis of the enzymes of the mandelate pathway by Pseudomonas putida. I. Synthesis of enzymes by the wild type. J. Bacteriol. 91:1140–1154. 1966.—The control of synthesis of the five enzymes responsible for the conversion of d(−)-mandelate to benzoate by Pseudomonas putida was investigated. The first three compounds occurring in the pathway, d(−)-mandelate, l(+)-mandelate, and benzoylformate, are equipotent inducers of all five enzymes. A nonmetabolizable inducer, phenoxyacetate, also induces synthesis of these enzymes; but, unlike the metabolizable inducer-substrates, it does not elicit synthesis of enzymes that mediate steps in the pathway beyond benzoate. Under conditions of semigratuity, dl-mandelate elicits immediate synthesis at a steady rate of the first two enzymes of the pathway, but two enzymes which act below the level of benzoate are synthesized only after a considerable lag. Succinate and asparagine do not significantly repress the synthesis of the enzymes responsible for mandelate oxidation.

Mechanisms of Oxygen Metabolism

Abstract: The enzymes which catalyze reactions of molecular oxygen occur in three principle classes: (i) oxygen transferases, (ii) mixed function oxidases, and (iii) electron transferases. The first class catalyzes the transfer of a molecule of molecular oxygen to substrate. The second class catalyzes the transfer of one atom of the oxygen to substrate; the other atom undergoes two-equivalent reduction. The third class catalyses the reduction of molecular oxygen to hydrogen peroxide or to water.

The beta-ketoadipate pathway.

Abstract: Publisher Summary β -ketoadipate pathway is considered one of the major microbial pathways for the dissimilation of aromatic and hydroaromatic compounds It provides a mechanism for the utilization of many different primary substrates, and offers a wide taxonomic distribution, both among bacteria and among fungi Various primary substrates dissimilated through this pathway are initially converted, through special reaction sequences, either to protocatechuic acid or to catechol These diphenols are regarded as the sites of entry to the two parallel and convergent branches of the β -ketoadipate pathway This chapter discusses the central reactions of the pathway—namely, those which result in the conversion of the two diphenolic intermediates to succinate and acetyl-CoA The most striking chemical feature of the bacterial β -ketoadipate pathway is the close chemical analogy between the successive metabolites of the catechol and protocatechuate branches, which differ only by the presence or absence of a carboxyl substituent The presence or absence of a carboxyl substituent on the substrates causes a major difference in chemical reactivity and imposes different requirements on the active sites of the enzymes operative in the two branches of the pathway