Heterogeneity and physiological activity of bovine k-casein proteolysis products

Gel chromatography in columns with Sephadex G-50 and biogel P-2 was used to separate a number of fractions formed in k-casein of cow's milk after short-term treatment with swine trypsin. These fractions, similar to beta-casomorphin, are capable of reducing the respiration and heart rates in rabbits after intravenous injection in a dose of 100 micrograms/kg, that suggests their capacity for interaction with opiate receptors. Some fractions injected subcutaneously induce in starving animals an electroencephalographic picture of satiation, similar to that observed after cholecystokinin injections. Correlation of amino acid composition and physiologic activity has evidenced that cholecystokinin and opioid effects are caused by different peptides.     

Glycopeptide obtained from k-casein and its effect on protein assimilation

The products of restricted proteolysis of kappa-casein were separated by gel filtration. Intravenous injection of high- and low-molecular fractions substantially reduced the pentagastrin-stimulated acid secretion in the anesthetized rat stomach. Intermediate fractions had lesser physiological activity. One of the active fractions administered intraintestinally inhibited acid secretion and reduced the pentagastrin-stimulated secretion in rat weanling isolated stomach. All the active fractions inhibited the stimulated secretion in rats with a ligated vagus. It is concluded that the nervous system does not play a crucial role in the mechanism by which gastric acid secretion is inhibited by the products of restricted proteolysis of kappa-casein. Decreasing acid secretion in the stomach, glycopeptide provides for the conditions favouring the efficacy of protein utilization at an early age. It is suggested that the effect of glycopeptide obtained from kappa-casein on the process of assimilation is mediated via peptide hormones.     

Conversion of linoleic acid hydroperoxide by soybean lipoxygenase in the presence of guaiacol: Identification of the reaction products

Linoleic acid hydroperoxide formed by soybean lipoxygenase was metabolized by the same enzyme in the presence of guaiacol. The products of this reaction included trihydroxyoctadecenoic acids, hydroperoxydihydroxyoctadecenoic acids, hydroxyepoxyoctadecenoic acids, dihydroxyoctadecenoic acids, hydroxyoctadecadienoic acids, and oxooctadecadienoic acids.     

Urban spatial adjustments resulting from rising energy costs

Since the 1973 oil embargo, the cost of energy in the United States has risen dramatically. The effect on the spatial structure of cities due to higher energy cost is the subject of this paper. Within the framework of a continuous general equilibrium model, it is demonstrated that, contrary to some previous studies, cities might be expected to decentralize rather than to centralize.