A versatile method for the synthesis of 5'-deoxy-8,5'-cycloadenosine, a conformationally-fixed "anti" type of adenosine, was presented. Irradiation of 2', 3'-O-isopropylidene-5'-deoxy-5'-phenylthioadenosine with 60W Hg vapor lamp afforded 2',3'-O-isopropylidene-5'-deoxy-8,5'-cycloadenosine in high yield. The use of other 5'-alkylthio derivatives also gave the cycloadenosine, though the yields were rather poor. Deacetonation of the cyclocompound with 0.1N HCl gave 5'-deoxy-8,5'-cycloadenosine. The cycloinosine derivative was similarly prepared. The nmr, mass and CD spectra of 5'-deoxy-8,5'-cycloadenosine were given and discussed with the previously reported results.

Adenosine↗

PubMed1976

Thermodynamic characteristics of the adsorption of sulfanilamide, phenol, and n-butanol on bio-gel beads.

The thermodynamic properties of the adsorption of sulfanilamide, phenol and n-butanol on Bio-Gel beads have been studied. Bio-Gel was chosen as the adsorbent as it possesses both hydrophobic and hydrophilic sites on its surface. Adsorption of the former two adsorbates was found to be exothermic, and the relevant thermodynamic parameters at 20 degrees are in the ranges: deltaH degrees = -2.7 to -5.4 kcal/mole; deltaF degrees = -6.0 to -7.6 kcal/mole; deltaS degrees = +7.7 to +11.6 e.u. In the presence of urea, adsorption of sulfanilamide and phenol was partially disrupted. This, together with the large entropy gain of the process, indicates that both hydrogen bonding and hydrophobic bonding contribute cooperatively to the adsorption. On the contrary, adsorption of n-butanol, which was not susceptible to urea, was an endothermic process with the parameters, deltaH degrees = +5.8kcal/mole, deltaF degrees = -1.8 kcal/mole, and deltaS = +26.1 E.U. at 20 degrees. These data conform to the thermodynamic properties of hydrophobic bond formation. Finally, possible implications of these data in the structural assembly of lipoprotein molecules are discussed.

Adsorption↗

PubMed1976

Additional evidence for hydrophobic bond formation in the adsorption of sulfanilamide on bio-gel beads.

We have previously suggested the involvement of both hydrogen binding and hydrophobic bonding in the adsorption of sulfanilamide on Bio-Gel beads. In the present study, we closely examined the concentration dependence of the binding curve and our proposed binding model has been corroborated. For comparison, binding parameters and thermodynamic data pertaining to the sulfanilamide-Sephadex system have been also evaluated.

Adsorption↗

PubMed1976

Circadian rhythms of digestive enzymes in the small intestine of the rat. II. Effects of fasting and refeeding.

The effects of fasting were examined on the rhythmic changes in the activities of maltase [EC 3.2.1.20] and leucine aminopeptidase [EC 3.4.11.1] in the small intestine of rats which has been kept under scheduled feeding conditions. Irrespective of whether the rats had been kept on a daytime or nighttime feeding schedule, the rhythms of maltase and leucine aminopeptidase persisted when the animals were starved. However, the amplitude of the leucine aminopeptidase rhythm began to decrease from the first day of fasting, while that of maltase did not. Conspicuous rhythms persisted for at least 2 days during fasting, but they gradually became vague and disappeared after 5 days. When rats were refed after fasting, the leucine aminopeptidase activity increased within a few hours, but the maltose activity did not. It is suggested that the rhythms of the digestive enzymes in the small intestine of rats are not a direct consequence of food intake, but are triggered off by the anticipatory mechanism which operates when rats expect to be fed. The rhythmic change of leucine aminopeptidase seemed to be intensified by food intake.

Animals↗

PubMed1976

Release of fatty acids from phosphatidylcholine by lecithin-cholesterol acyltransferase.

Partially purified lecithin-cholesterol acyltransferase [EC 2.3.1.43] from human plasma released fatty acids from phosphatidylcholine. Heating, sulfhydryl reagents, Ca2+, EDTA, and sodium deoxycholate had similar effects on the lecithin-cholesterol acyltransferase and fatty acid releasing activities of the preparation. A specific cofactor protein for lecithin-cholesterol acyltransferase, apoA-1, also enhanced both activities. Release of fatty acid was due to enzymatic hydrolysis of the ester linkage at carbon-2 of phosphatidylcholine. It is suggested that the two activities are due to a single enzyme.

Acyltransferases↗

PubMed1976

The bark-eating habits in primates, with special references to their status in the diet of wild chimpanzees.

Chimpanzees of the Mahali Mountains, Tanzania, were recorded to chew barks of 21 species of trees and wood vines. They mainly utilize the barks of savanna-living deciduous trees during the mid-rainy season of the year when few fruits are available. The degree of their dependence on bark for food varies drastically year by year. The bark seems to occupy an important role as emergency food in a lean year in the survival of chimpanzees, as well as in that of some other higher primates.

Animals↗

PubMed1976