Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10533811 | Analytical Biochemistry | 2005 | 9 Pages |
Abstract
Tacrolimus (FK506) is a hydrophobic immunosuppressive agent used in kidney, liver, and lung transplantation. The objective of this study was to characterize the binding of FK506 to surfactant protein A (SP-A), an abundant lipoprotein found in the alveolar fluid that functions as part of the innate immune system in the lung. We have synthesized a novel derivative of FK506 in which a dansyl moiety was covalently bound via cadaverine to the C22 position of the FK506 molecule (DNS-FK). Using the fluorescence and anisotropy properties of DNS-FK, we demonstrated that tacrolimus avidly binds to SP-A with an apparent equilibrium association constant (Kapp) of 107Â Mâ1 and a Gibbs binding free energy of â40Â kJÂ molâ1Â Kâ1. Derivatization of FK506 at the C22 position did not block FK506 binding to the cytosolic immunophilin FK506-binding protein (FK-BP) or human serum albumin (HSA), both used as controls of tacrolimus-binding proteins. Kapp for FK-BP/DNS-FK and HSA/DNS-FK complexes were 1.5Â ÃÂ 107 and 107Â Mâ1, respectively. The high sensitivity of this analytical technique makes it suitable for binding analysis of FK506 to proteins.
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Olga Cañadas, Alejandra Sáenz, Guillermo Orellana, Cristina Casals,