Binding of carbohydrates to solid supports: evaluation of a prototype system.

Mono- and disaccharides were covalently and irreversibly bound to aminopolystyrene beads in good yield by heating in dilute aqueous solution. The degree and stability of sugar binding were determined by chemical and radiochemical methods and the accessibility of the bound sugars was demonstrated by exoglycosidase hydrolysis and by an enzyme-linked lectin-binding assay using Concanavalin A.

A distinct diurnal rhythm in hydroxyindole-O-methyltransferase (HIOMT) activity in the male albino rat.

Pineal hydroxyindole-O-methyltransferase (HIOMT) has been reported to show a diurnal rhythm activity in the rat, although this is not fully confirmed. The present study reexamines this issue and reports a distinct diurnal rhythm in rat pineal HIOMT. Peak enzyme activity occurs 5 hr after the onset of darkness, followed by two lesser bursts of activity preceding each change in the photoperiod.

Formation of peroxides in amino acids and proteins exposed to oxygen free radicals.

Dilute aqueous solutions of BSA or lysozyme gave positive tests for peroxides after exposure to reactive oxygen species. The reactive species were generated by gamma-irradiation, reduction of H2O2 with Fe2+ ions or thermal decomposition of an azo compound. Peroxides were assayed by an iodometric method.

The release of corticosterone and a corticosterone-binding protein by incubated rat adrenal slices.

Stimulation of incubated rat adrenal slices with ACTH(1-24) resulted in an increase in the release of both corticosterone and specific corticosterone-binding protein into the incubation medium. The release of corticosterone and binding protein was dose and calcium dependent with adrenals from animals pretreated with betamethasone. While the secretion of corticosterone was continuous throughout the incubation period, there appeared to be a limit to the increase in binding capacity.

Adrenocorticotropin binding sites in rat cardiac tissue.

Using the ACTH analog [125I-Tyr23,Phe2,Nle4] ACTH(1-24), the existence of specific binding sites for ACTH in atrial membrane preparations was demonstrated. The dissociation constants (Kd), determined by Scatchard analysis were not significantly different for membrane preparations of adrenal gland or atrial tissue (being 6.40 x 10(-12)M and 8.