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D Atlas

Publications and source records attributed to D Atlas.

99 records · Page 6Linked to original sources
PubMed1974

Stereospecific binding of propranolol and catecholamines to the beta-adrenergic receptor.

The stereospecificity of the beta-adrenergic receptor of turkey erythrocyte ghosts was studied. Binding of the specific beta-adrenergic antagonist, propranolol, was found to occur exclusively with the l-stereoisomer. The stereospecificity of catecholamine binding was determined by assaying the ability of the catecholamines to displace [(3)H]propranolol. Binding of the catecholamines was also found to be stereospecific for the l-stereoisomers. Furthermore, the d-stereoisomers do not compete with the l form for binding. Using this displacement technique, we were able to calculate the dissociation constants for l-epinephrine, l-norepinephrine, and l-isoproterenol from the beta-receptor and compare these values to the apparent dissociation constants obtained from the direct activation of adenylate cyclase (EC 4.6.1.1) by these catecholamines.

Animals↗
PubMed1974

The binding characteristics and number of beta-adrenergic receptors on the turkey erythrocyte.

Turkey erythrocyte ghosts (empty membranes) possess a class of receptors that can bind both L-[(3)H]isoproterenol and DL-[(3)H]propranolol. The binding of [(3)H]isoproterenol to these receptors occurs with a dissociation constant of 0.15 muM and can be fully inhibited by 1 muM propranolol. The binding of [(3)H]propranolol occurs with a dissociation constant of 2.5 nM and can be fully inhibited by 0.2 mM DL-isoproterenol. Ligand binding is sensitive to sonication, boiling, and 8 M urea. The cells possess 500 to 1000 beta-adrenergic receptors per cell. Binding of propranolol to the beta-receptor was found to be stereospecific for the L stereoisomer. If one assumed a 1:1 relationship between beta-adrenergic receptors and adenylate cyclase, the turnover number of this adenylate cyclase would be close to 100 min(-1).

Adenylyl Cyclases↗
PubMed1970

On the active site of elastase: Partial mapping by means of specific peptide substrates.

RNase-S peptide as well as some related octa- and hexapeptides were found to be highly, reactive substrates of porcine elastase (e.g. Ala(4)-Lys-Phe: K(m) = 4500 M(-1), k(cat) = 32 sec(-1), C = 1.4 x 10(5) M(-1) sec(-1)). Comparison of the various peptides led to the conclusion that the active site of porcine elastase is composed of 6-7 subsites (c.f. [1]). Preliminary mapping shows that subsites S(2), S'(1) and S'(2) have hydrophobic character. Occupation of subsite S(4) by the substrate is important for efficient hydrolysis. Binding at this subsite was found to be stereospecific.

Journal Article↗
PubMedDate not supplied

Direct evidence for absence of beta-adrenergic receptors in rat cerebral vessels histochemical study with a fluorescent beta-blocker.

A fluorescent marker for beta-adrenergic receptor sites, 9-amino-acridin propranolol (9-AAP), was administered intravenously to rats. In contrast to other tissues which are known to contain beta-adrenergic receptors, 9-AAP fluorescence was not observed in the walls of the pial as well as parenchymal cerebral vessels. These negative findings strongly suggest that in the rat, beta-adrenergic receptors are not present in the cerebral vasculature. The role of the alpha-adrenergic receptors needs more study.

Animals↗