title: Design of rhenium(I) polypyridine biotin complexes as a new class of luminescent probes for avidin.
abstract: This paper describes the design of a series of luminescent rhenium(I) polypyridine biotin complexes containing different spacer-arms, [Re(N-N)(CO)3 (py-4-CH2-NH-biotin)](PF6) (py-4-CH2-NH-biotin = 4-(biotinamidomethyl)pyridine; N-N = 1,10-phenanthroline, phen (1a), 3,4,7,8-tetramethyl-1,10-phenanthroline, Me4-phen (2a), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, Me2-Ph2-phen (3a), dipyrido[3,2-f:2',3'-h]quinoxaline, dpq (4a)), [Re(N-N)(CO)3 (py-3-CO-NH-en-NH-biotin)](PF6) (py-3-CO-NH-en-NH-biotin = 3-(N-((2-biotinamido)ethyl)amido)pyridine; N-N = phen (1b), Me4-phen (2b), Me2-Ph2-phen (3b), dpq (4b)), and [Re(N-N)(CO)3 (py-4-CH2-NH-cap-NH-biotin)](PF6) (py-4-CH2-NH-cap-NH-biotin = 4-(N-((6-biotinamido)hexanoyl)aminomethyl)pyridine; N-N = phen (1c), Me4-phen (2c), Me2-Ph(2)-phen (3c), dpq (4c)). Upon irradiation, all of the rhenium(I)-biotin complexes exhibited intense and long-lived triplet metal-to-ligand charge-transfer (3MLCT) (d pi(Re) --> pi* (diimine)) emission in fluid solutions at 298 K. The interactions of these biotin-containing complexes with avidin have been studied by 4'-hydroxyazobenzene-2-carboxylic acid (HABA) assays, emission titrations, and competitive association and dissociation assays. On the basis of the results of these experiments, homogeneous assays for biotin and avidin have been designed.
authors.affiliation: Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People's Republic of China. bhkenlo@cityu.edu.hk
authors.forename: Kenneth Kam-Wing
authors.initials: KK
authors.lastname: Lo
authors.forename: Wai-Ki
authors.initials: WK
authors.lastname: Hui
mesh_terms: D001360:Avidin; D001665:Binding Sites; D001710:Biotin / Q000737:chemistry*; D002384:Catalysis; D015195:Drug Design; D005456:Fluorescent Dyes; D008163:Luminescent Measurements / Q000379:methods*; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D012211:Rhenium / Q000737:chemistry*
chemical_list: D005456:Fluorescent Dyes; D011108:Polymers; D011725:Pyridines; D001360:Avidin; D001710:Biotin; D012211:Rhenium; C023666:pyridine