title: Production and characterization of a monoclonal antibody against the beta-adrenergic agonist ractopamine.
abstract: A monoclonal antibody was generated toward the beta-adrenergic agonist ractopamine hydrochloride ¿(1R,3R),(1R, 3S)-4-hydroxy-alpha-[[[3-(4-hydroxyphenyl)-1-methylpropyl]amino]methy l]benzenemethanol hydrochloride¿. Ractopamine-glutarate-keyhole limpet hemocyanin (KLH) was used as the antigen for antibody generation in mice. Clone 5G10, secreted antibody with isotype IgG1kappa, was used for the development of an immunoassay. The selected antibody was specific for racemic ractopamine with an IC(50) of 2.69 +/- 0.36 ng/mL (n = 15). Antibody binding toward ractopamine was stereoselective with (1R,3R)-ractopamine having an IC(50) of 0.55 +/- 0.09 ng/mL (n = 3). IC(50) values for the (1S, 3R)-, (1S,3S)-, and (1R,3S)-ractopamine stereoisomers were 2.00 +/- 0.37, 140 +/- 23, and 291+/- 32 ng/mL (n = 3), respectively. Phenethanolamine beta-agonists showed low cross-reactivity. Studies using a series of ractopamine metabolites and ractopamine analogues demonstrated structural requirements for the antibody binding. A free phenolic group on the N-butylphenol moiety was required for high-affinity binding because methoxylated analogues and metabolites glucuronidated at this phenol generally had IC(50) values greater than 200 ng/mL. Ractopamine analogues methoxylated or glucuronidated at the ethanolamine phenol had IC(50) values of 0.7-2.6 ng/mL. Lack of a benzylic hydroxyl group was of less importance to antibody binding than was the correct stereochemical orientation (3R) of ractopamine's N-phenylalkyl group. In conclusion, a highly specific monoclonal antibody to ractopamine hydrochloride was developed that could be of potential utility in screening assays.
authors.affiliation: Agricultural Research Service, U.S. Department of Agriculture, 5674 University Station, and Department of Veterinary and Microbiological Sciences, North Dakota State University, Fargo, North Dakota 58105, USA. shelverw@fargo.ars.usda.gov
authors.forename: W L
authors.initials: WL
authors.lastname: Shelver
authors.forename: D J
authors.initials: DJ
authors.lastname: Smith
authors.forename: E S
authors.initials: ES
authors.lastname: Berry
mesh_terms: D000318:Adrenergic beta-Agonists / Q000276:immunology*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis* / Q000276:immunology; D003429:Cross Reactions; D007118:Immunoassay; D051379:Mice; D010627:Phenethylamines / Q000276:immunology*
chemical_list: D000318:Adrenergic beta-Agonists; D000911:Antibodies, Monoclonal; D010627:Phenethylamines; C060897:ractopamine