title: Dissociative binding of alpha- and beta-sulphoxides of biotinylamidoethyl-3-(4-hydroxy-3-[125I]iodophenyl)propionamide to avidin.
abstract: Previously we reported the dissociative binding of biotinylamidoethyl-3-(4-hydroxy-3-[125I]iodophenyl)propionamide to avidin [Garlick & Giese (1988) J. Biol. Chem. 263, 210-215]. In the present paper we report the corresponding binding of the alpha- and beta-sulphoxides of this parent compound to avidin. The 1:1 complex (obtained with avidin in excess) of the alpha-sulphoxide derivative with avidin has a dissociation half-life (t1/2) of 25 days, only 1.6 times as fast as the parent compound (t1/2 41 days). However, the corresponding beta-sulphoxide dissociates 446 times faster (t1/2 0.092 day) than the parent compound, this apparently being due to a steric effect. The alpha-sulphoxide is attractive as a tracer reagent to facilitate studies and applications of the avidin-biotin system.
authors.affiliation: Department of Medicinal Chemistry, College of Pharmacy and Allied Health Professions, Northeastern University, Boston, MA.
authors.forename: R K
authors.initials: RK
authors.lastname: Garlick
authors.forename: R W
authors.initials: RW
authors.lastname: Giese
mesh_terms: D001360:Avidin / Q000378:metabolism*; D001710:Biotin / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000378:metabolism*; D055598:Chemical Phenomena; D002621:Chemistry; D007202:Indicators and Reagents / Q000378:metabolism*; D013454:Sulfoxides / Q000138:chemical synthesis / Q000378:metabolism*
chemical_list: D007202:Indicators and Reagents; D013454:Sulfoxides; C064794:biotinylamidoethyl-3-(4-hydroxy-3-iodo-phenyl)propionamide alpha-sulfoxide; C064818:biotinylamidoethyl-3-(4-hydroxy-3-iodophenyl)propionamide beta-sulfoxide; D001360:Avidin; D001710:Biotin