The intracellular localization of Pseudomonas aeruginosa lectins

The localization of the Pseudomonas aeruginosa lectins (PA-I and PA-II) was studied using methods of osmotic shock, freezing and thawing and spheroplast formation. Very slight release of the two lectins occurred when P. aeruginosa was exposed to magnesium-osmotic shock or was frozen and thawed. Under these conditions, release of the periplasmic 5'-nucleotidase occurred, whereas no release of cytoplasmic glucose-6-phosphate dehydrogenase activity was detected. Formation of spheroplasts from P. aeruginosa by gradual removal of the bacterial envelopes revealed low lectin activity in the treatment fluids. Osmotic shock treatment of the lysozyme treated mureinoplasts resulted in low release of glucose-6-phosphate dehydrogenase and the two lectins (10-13%) and a considerable activity (38.4%) of 5'-nucleotidase. The presence of the lectins on the outer and the cytoplasmic membranes enabled intact cells and spheroplasts of P. aeruginosa to agglutinate papain-treated human erythrocytes. These results indicate that the two lectins are located mainly in the cytoplasm with small fractions on the cytoplasmic and outer membranes and in the periplasmic space.     

Circadian rhythms of alcohol dehydrogenase and MEOS in the rat

The circadian peak in alcohol dehydrogenase (ADH) activity fell near the time of maximal blood ethanol clearance rates both in groups of rats injected with a single ethanol dose (acute group) and in rats continuously exposed to ethanol for 22 weeks (chronic group). However, at all timepoints investigated ADH activity levels were lower and fluctuated less in the chronic group than in either the acute or control (ethanol naive) groups. In contrast, activity levels of the microsomal ethanol oxidizing system (MEOS) revealed a prominent rhythm that was 180 degrees out of phase with the ADH rhythm in the chronic group, while MEOS activity showed very low levels in the acute and control groups and did not vary over the circadian span.     

A radiometric assay of pyridoxamine (pyridoxine) 5′-phosphate oxidase

A radiometric assay for pyridoxamine 5′-phosphate oxidase (pyridoxamine (pyridoxine) 5′-phosphate:O₂ oxidoreductase (deaminating), EC 1.4.3.5) has been developed utilizing N-(5′-phosphopyridoxyl)[³H]tryptamine. This assay is more sensitive than previously used colorimetric and fluorescent assays for this oxidase and furthermore is applicable to erythrocytes. Tritiated substrate is incubated with an enzyme sample in the presence of excess unlabeled truptamine and the radiolabeled tryptamine product is extracted into toluene and quantitated by liquid scintillation counting.