Isolation and properties of L-amino acid oxidase from Ophiophagus hannah venom

This paper reports the isolation and some properties of L-amino acid oxidase from Ophiophagus hannah venom. The differences between L-amino acid oxidase from Ophiophagus hannah and that from other sources in specific activity, properties and the spectrum of isozymes are noticeable. The result of electrophoresis on polyacrylamide gel shows that this purified enzyme is homogenous. The molecular weight determined by gradient polyacrylamide gel slab (4--30%) is around 15 X 10(4) dalton. The molecular weight of the subunit determined by SDS gradient gel electrophoresis (4--30%) is around 7.3 X 10(4) dalton. Therefore, this enzyme is composed of two subunits. The absorption spectrum reveals that there are two FADs in each molecule. The optimum pH of enzymic reaction is around 8.7--9.0 when L-leucine is used as substrate. The inhibition of the products is noticeable when substrate concentration goes beyond 3mM. This enzyme is heat stable and its activity would not decrease obviously after heating at 55 degrees C for 40 min. A linear relationship between enzyme concentration and reaction rate was noticed when enzyme concentration was below 5.7 micrograms/ml.

Molecular motion of DNA as measured by triplet anisotropy decay

We have used triplet anisotropy decay techniques to measure the internal flexibility and overall rotational motion of DNA, covering a time range from 15 ns to 200 mus. Nearly monodisperse DNA fragments 65--600 base pairs long were studied by using the intercalating dye methylene blue as a triplet probe. We found that the slow end-over-end tumbling of short DNA fragments (less than or equal to 165 base pairs) is as predicted for a rigid rod. As expected, a longer DNA fragment (600 base pairs) experiences slow segmental motion of its helix axis. We found that, at the earliest times, anisotropy decays more rapidly than expected for a rigid rod, suggesting that, when bound, methylene blue monitors fast internal motion of the helix. Since the rod-like end-over-end tumbling of short fragments rules out fast bending motions, we conclude that the fast components of DNA anisotropy decay are due to twisting motion of the helix, occurring with a time constant near 50 ns.

Body composition in affective disorder before, during, and after lithium carbonate therapy

The body composition of three unipolar and 17 bipolar patients, studied during the depressive state, was compared with that of 48 controls. The ratio of extracellular to intracellular water content was significantly less in male patients than in male controls: the difference between female patients and female controls was not statistically significant. In patients of both sexes, residual sodium concentration was greater in patients than in controls. The intracellular content of potassium was the same in patients as in controls. In six patients, body composition was studied prior to lithium carbonate therapy, after 17 days of treatment, and 17 days after discontinuing administration of the drug. The significant changes were a decrease in body weight during therapy, and a decrease in body water content and an increase in residual sodium concentration after drug treatment was discontinued.

Body composition measurements in normal man: the potassium, sodium, sulfate and tritium spaces in 58 adults

The aqueous phase of total body composition varies with sex, and changes with age, necessitating age, sex and method-specific normal values. Consensus has developed for the methods most suited to clinical studies. 3H20 for water, 35SO4 for ECW, 24Na for NAc, and 40K for body potassium were used in 58 normal volunteers aged 19-80, 30 men and 28 women. This report shows significant age regressions in both sexes for total body water and intracellular water, and for both Na and K when referenced to body water. Combination of these findings with the highly age related decrease in total body potassium confirms previous studies that body cell mass decreases with age. Intracellular K+ and Na+ at the zero age intercept are 130 and 14.5 for males, and 124 and 24mEq/1 for females respectively. Secular decrease in K+ and increase in Na+ concentrations in the average cell are suggested although not established. Values for normal body composition, in subjects healthy by all available criteria are in some instances age and sex dependent, but in all parameters except fat show wide normal range (SD = 7% of mean) which derive more from biological variation than from limitations of measurement precision. However, use of body water rather than weight succeeds in narrowing this wide range, and is a more logical denominator which is readily subject to accurate measurement. In serial studies of the same subject, significant changes can be measured which are well within the normal range.

A possible low intracellular potassium in obesity

In comparison with lean marathon runners whose fat content was 15%, obese subjects with a fat content of 55% showed a 36% reduction in intracellular potassium. It is hypothesized that as much as 60% of this decrease may have been due to the lower proportion of muscle (which has the highest intracellular potassium of any tissue) in the fat free mass of very obese subjects. The remainder of the decrease seems to have been a measurement artefact owing to self-absorption of gamma rays by adipose tissue, most of which is distributed over potassium rich lean tissue. The low intracellular potassium values found in obesity should not be interpreted as necessarily signifying potassium deficiency.

Combined effects of alcohol and lithium on body composition in the rat model

Alcohol markedly enhances Li+ retention in blood and muscle in rats taking Li and alcohol. The marked enlargement of the exchangeable Na+ space which occurs with alcohol alone, Li+ alone, and to an even greater extent with combined therapy, results from extensive mobilization of "bound" bone sodium, which is transferred to intracellular sites, demonstrably in skeletal muscle, and presumably in other cells. This 87% increase in measured intracellular Na+, and concomitant decrease in K+, would be predicted to produce profound effects on the intracellular ionic milieu, and on membrane function. Lithium is associated with a decrease in food and fluid intake, and this effect is enhanced by alcohol. However the decrease in intake did not result in nutritionally significant deficits in either group, and therefore the observed abnormalities in body composition did not result from caloric, protein, K, Na, or Ca deficiency.

Metabolism of calf trabecular (reticular) meshwork

It has been found that calf eyes are an excellent source of trabecular meshwork tissue for biochemical studies. Homogenates of pooled meshwork were centrifuged at 27K X g and 1.5K X g. The high-speed supernatants produced lactate at 0.35 mumole/min/gm tissue in the presence of hexokinase-saturating concentrations of glucose (10 mM) at pH 7. The optimum pH was 7.6. In the absence of ammonia, lactate could be produced from fructose 1,6-diphosphate but not from glucose or glucose 6-phosphate. The optimum ammonia concentration was 1 to 2 mM. Lactate was produced at an even greater rate from fructose, but only poorly from sorbitol or galactose (all at 10 mM). The activity of hexokinase, glucose 6-phosphate dehydrogenase and UDPG dehydrogenase was measured. Fructokinase could not be detected. The low-speed supernatant readily oxidized succinate, malate, and glutamate at about 0.012 muAtO/min/gm tissue. The oxidative rate in vivo is estimated to be about one third of this. These results demonstrate that knowledge of the normal metabolism of calf trabecular meshwork may be obtained with relative ease, with possible important implications for understanding the disease of glaucoma.

Effect on body water of running 10 miles

Despite a 2.3% weight loss in 10 men who ran 10 miles, extracellular water (ECW) increased by 3.5%. Total body water (TBW) measured as tritium space increased by 2.4%, and intracellular water (ICW), inferred as the difference between TBW and ECW, increased by 1.8%. The increase in tritium space probably represents increased nonaqueous hydrogen exchange in the postexercise period ond casts doubt on the validity of TBW and ICW when measured immediately after exercise.