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Biomedical subjects

N J Cartwright

Publications and source records attributed to N J Cartwright.

11 recordsLinked to original sources
PubMed1977

Bacterial attack on phenolic ethers. Purification and characterization of the components of the meta O-dealkylase of Pseudomonas fluorescens Tp.

The meta O-dealkylase of Pseudomonas fluorescens Tp has been resolved into two protein components, neither of which is a cytochrome. The substrate binding terminal oxidase has been purified and shown to be a non-haem iron protein of approximate molecular weight 118,000, consisting of two seemingly identical subunits, each of molecular weight 55,000. Binding of substrate by the terminal oxidase has been established by difference spectroscopy. The amino acid composition of the protein has also been determined. The NADH-dependent reductase of the system has been partly purified and appears to have a molecular weight of 80,000. The similarity between this and other bacterial O-dealkylases is discussed.

Amino Acids↗
PubMed1967

Bacterial attack on phenolic ethers: An enzyme system demethylating vanillic acid.

1. A cell-free system from Pseudomonas fluorescens catalysed the oxidative demethylation and subsequent ring-cleavage of vanillate, with uptake of 2.5 moles of oxygen/mole of substrate. 2. Demethylation involved absorption of 0.5 mole of oxygen/mole, and required reduced glutathione (GSH) and nucleotide (probably NADPH) as cofactors, with further possible requirements, the natures of which are discussed. 3. Incomplete evidence suggested that the aromatic ring was opened via protocatechuate and the appropriate oxygenase, with absorption of 1 mole of oxygen/mole of substrate, eventually yielding beta-oxoadipate. 4. The methyl group was removed sequentially as formaldehyde, formate and carbon dioxide, the steps catalysed respectively by formaldehyde dehydrogenase, which required GSH and NAD(+), and formate dehydrogenase. Each enzyme was cytochrome-linked and accounted for absorption of 0.5mole of oxygen/mole of substrate. 5. All enzymes except formate dehydrogenase, which was a cell-wall enzyme, resided in the soluble fraction of the extract. The demethylase could not be resolved because of unknown cofactor requirements.

Journal Article↗
PubMed1967

The separation of vanillate O-demethylase from protocatechuate 3,4-oxygenase by ultracentrifugation.

1. Protocatechuate 3,4-oxygenase in the soluble part of a cell-free extract of Pseudomonas fluorescens (strain T) sedimented more rapidly than vanillate O-demethylase under specified conditions in a preparative ultracentrifuge. 2. The supernatant from this process contained vanillate O-demethylase and formaldehyde dehydrogenase, and when supplemented with NADH oxidized vanillate with an uptake of 1 mole of oxygen/mole of substrate and accumulation of protocatechuate. 3. This uptake was decreased to 0.5mole/mole of substrate in the presence of semicarbazide as trapping agent for formaldehyde. 4. Reasons are presented for the process of methyl group removal from vanillate being oxidative demethylation.

Cell-Free System↗