Thermodynamic analysis of cyclosporin a binding to cyclophilin a in a lung tumor tissue lysate.
We report on the application of SUPREX (stability of unpurified proteins from rates of H/D exchange) to the analysis of a protein-ligand binding interaction under the ex vivo solution conditions of a human lung tumor tissue lysate. A SUPREX-derived binding free energy (i.e. DeltaDeltaG(f) value) and dissociation constant (i.e., K(d) value) were determined for the binding of cyclosporin A (CsA) to a cyclophilin A (CypA) sample in which the protein was a component of a tissue lysate derived from fresh frozen lung tumor. The DeltaDeltaG(f) and K(d) values determined by SUPREX for CsA binding to CypA in this unpurified protein sample, 4.7 +/- 0.8 kcal/mol and 77 +/- 17 nM, respectively, were comparable to the those obtained when SUPREX was used to analyze the binding of CsA to a highly purified CypA sample, 4.2 +/- 1.0 kcal/mol and 32 +/- 20 nM, respectively. Moreover, the SUPREX-derived K(d) values determined in this work were both in the range of those previously reported for the CypA-CsA complex. The results of this proof-of-principle work validate the extension of SUPREX to the thermodynamic analysis of proteins and protein-ligand binding interactions in the unpurified, ex vivo conditions of human tissue lysates,and they represent the first K(d) measurement on a protein-ligand complex under such conditions
Department of Chemistry, Duke University, Box 90346, Durham, North Carolina 27708, USA.
Michael Z
MZ
Wang
Jagat T
JT
Shetty
Brandon A
BA
Howard
Michael J
MJ
Campa
Edward F
EF
Patz
Michael C
MC
Fitzgerald
D021984:Cyclophilin A / Q000378:metabolism*; D016572:Cyclosporine / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008175:Lung Neoplasms / Q000378:metabolism* / Q000601:surgery; D013816:Thermodynamics
D016572:Cyclosporine; D021984:Cyclophilin A