Evidence about the catecholoxidase activity of the enzyme ascorbate oxidase extracted from Cucurbita pepo medullosa.

Pure ascorbate oxidase (L-ascorbate:oxygen oxidoreductase, EC 1.10.3.3) isolated from Cucurbita pepo medullosa, which is known to be specific for ascorbic acid, shows a secondary catecholoxidase activity at approx. pH 6.7. This activity was tested against natural and synthetic compounds possessing a catechol-like structure. Among natural compounds (+)-catechin furnishes the same complex oxidation mixture obtained with other oxidases. Among synthetic compounds, 3,5-di-t-butylcatechol and 4-t-butylcatechol give the corresponding o-quinones. The significance of this secondary activity in the darkening process of fruits and vegetables which contain ascorbate oxidase is also discussed.

Isolation of a Pseudomonas stutzeri strain that degrades o-xylene.

A Pseudomonas stutzeri strain capable of growing on o-xylene was isolated from enrichment cultures. The organism grew on 2,3- and 3,4-dimethylphenol but not on 2-methylbenzyl alcohol, o-tolualdehyde, or o-toluate. P. stutzeri was not able to utilize m-xylene, p-xylene, or 1,2,4-trimethylbenzene, but growth was observed in the presence of the corresponding alcohols and acids. From the Pseudomonas cultures supplied with o-xylene, 2,3-dimethylphenol was isolated and identified. When resting P. stutzeri cells were incubated with 2,3-dimethylphenol, the reaction mixture turned greenish yellow and showed spectral properties identical to those of the 3,4-dimethylcatechol meta ring fission product. Catechol 2,3-oxygenase was induced by growth on o-xylene or on 2,3- or 3,4-dimethylphenol. The suggested hypothesis is that the first metabolic steps of growth on o-xylene involve the direct oxygenation of the aromatic nucleus, followed by meta pathway reactions.

The rate of N-demethylation of N,N-dimethylanilines and N-methylanilines by rat-liver microsomes is related to their first ionization potential, their lipophilicity and to a steric bulk factor.

The N-demethylation of a series of 12 p-substituted N,N-dimethylanilines, nine m-substituted N,N-dimethylanilines, one o-substituted N,N-dimethylaniline and four p-substituted N-methylanilines by rat-liver microsomes was studied. For each compound, the apparent Vmax and Km values were determined and these parameters were correlated with their electronic, lipophilicity and steric bulk parameters reported in the literature. Multi-parameter linear regression analysis showed a good correlation between log Vmax and these parameters for the p-substituted N,N,-dimethylanilines. A lower degree of correlation was observed with the meta-substituted N,N-dimethylanilines.

The microbial oxygenation of the benzylisoquinoline alkaloid laudanosine.

The microbial transformation of the benzylisoquinoline alkaloid laudanosine by a strain of Pseudomonas putida gives a metabolite in which O-demethylation of 1 methoxyl group of ring C, and introduction of 1 ketonic oxygen at C9 and 1 phenolic oxygen at ring C have occurred. Also, O-methylcoripalline is formed in this transformation.

Analysis of allergenic components of a Parietaria judaica pollen extract by chromatographic methods for the evaluation of purification procedures.

Size-exclusion and ion-exchange high-performance liquid chromatography were used to monitor the presence of polymeric aggregates and of families of allergens of similar isoelectric point in Parietaria judaica pollen extracts. A radio-allergo-sorbent test and chromatofocusing were used for the analysis of individual fractions. This allows the detection of two groups of allergens, having pI of 4.7 and greater than 5.7, respectively, and shows the effect of dialysis or ultrafiltration on the distribution of allergens.

Purification and molecular weight studies on the components of a Parietaria pollen extract.

The pollen extract of the allergenic plant Parietaria judaica, growing throughout the Mediterranean region, has been purified by high performance liquid chromatography (HPLC) operating in size-exclusion followed by ion exchange. Molecular weight determination of the components and isoelectrofocusing studies on the enriched material have been performed.

Micropreparative-scale enrichment of some allergenic components of Parietaria pollen extract.

A preparative-scale enrichment of the allergenic components of the pollen extract of Parietaria judaica, which grow all over the Mediterranean area, has been obtained by high-performance liquid chromatography, operating in the ion-exchange mode at pH 7 with a curvilinear ionic-strength gradient.