Photoaffinity labeling adenosine A1 receptors with an antagonist /sup 125/I-labeled aryl azide derivative of 8-phenylxanthine

Journal Article · Thu Mar 31 23:00:00 EST 1988 · J. Med. Chem.; (United States)

DOI:https://doi.org/10.1021/jm00399a011· OSTI ID:7154845

Earl, C Q; Patel, A; Craig, R H; Daluge, S M; Linden, J

We have derivatized a series of /sup 125/I-labeled 8-phenylxanthines with photoactive aryl azide groups on the 1- or 3-position of the xanthine ring. A 3-azidophenethyl derivative was found to be optimal for use as an antagonist photoaffinity label for adenosine A1 receptors. Following photoactivation, radioactivity was covalently and specifically incorporated into a 34,000-dalton and, to a lesser extent, into a 24,000-dalton polypeptide of rat brain membranes. Photoincorporation into both polypeptides was competitively inhibited by adenosine analogues with a potency order typical of adenosine A1 receptors, but the 24,000-dalton polypeptide bound both agonists and antagonists with lower affinity than the 34,000-dalton polypeptide. Specific photolabeling of receptors in brain membranes of rat, guinea pig, dog, and cow did not show any variation in the 34,000-dalton adenosine receptor binding subunit. The adenosine agonist photoaffinity label (/sup 125/I)N6-(4-azido-3-iodobenzyl)adenosine also specifically photolabeled the 34,000-dalton polypeptide, but photoincorporation of the agonist was less efficient than the antagonist and, unlike the antagonist, was greatly reduced by guanosine 5'-(beta,gamma-imidotriphosphate). The results indicate that the antagonist photoaffinity label may be more useful than agonists particularly for labeling uncoupled receptors.

• Research Organization: Univ. of Virginia School of Medicine, Charlottesville (USA)
• OSTI ID: 7154845
• Journal Information: J. Med. Chem.; (United States), Journal Name: J. Med. Chem.; (United States) Vol. 31:4; ISSN JMCMA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADENOSINE
AFFINITY
ANIMALS
AROMATICS
AZAARENES
AZIDES
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BODY
BRAIN
CATTLE
CELL CONSTITUENTS
CELL MEMBRANES
CENTRAL NERVOUS SYSTEM
CHEMISTRY
DAYS LIVING RADIOISOTOPES
DOGS
DOMESTIC ANIMALS
ELECTRON CAPTURE RADIOISOTOPES
GUINEA PIGS
HETEROCYCLIC COMPOUNDS
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LABELLING
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
MOLECULAR WEIGHT
NERVOUS SYSTEM
NITROGEN COMPOUNDS
NUCLEI
NUCLEOSIDES
NUCLEOTIDES
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANS
PEPTIDES
PHOTOCHEMISTRY
POLYPEPTIDES
PROTEINS
PURINES
RADIOISOTOPES
RATS
REACTION KINETICS
RECEPTORS
RIBOSIDES
RODENTS
RUMINANTS
STRUCTURE-ACTIVITY RELATIONSHIPS
TRACER TECHNIQUES
VERTEBRATES
XANTHINES