Studies on the interactions of kaempferol to calcineurin by spectroscopic methods and docking.
Kaempferol, in our previous study, was a new immunosuppressant on calcineurin (CN), the Ca(2+)/calmodulin (CaM)-dependent protein phosphatase. Here, we examined the interactions of kaempferol with CN by fluorescence spectroscopy (FS), circular dichroism spectroscopy (CD) and docking. Data of kaempferol with CN catalytic subunit (CN A) and its truncated mutant CNAa obtained by FS method showed that the binding stoichiometry of kaempferol/CN A was 1:1, catalytic domain of CN A was the concrete domain for kaempferol binding while other domains contributed a lot to this binding. Distances from kaempferol to each tryptophan (Trp) in CN A by energy transfer experiments and the subsequent docking study interestingly provided the same binding sites for kaempferol, which all located in the non-active site area of CN A catalytic domain, also consisted with our previous conclusion from CN activity assay. Furthermore, CD results showed a much tighter structure of CN A for the inhibitor binding; on the other hand, presence of Ca(2+) and Mn(2+) decreased kaempferol binding on CN A.
Lei
Hong
H
Department of Biochemistry and Molecular Biology, Beijing Normal University, Beijing Key Laboratory, Beijing, China.
Qi
Yao
Y
Jia
Zhi-Guang
ZG
Lin
Wei-Lin
WL
Wei
Qun
Q
D019703:Calcineurin / Q000235:genetics / Q000378:metabolism*; D065095:Calcineurin Inhibitors; D002118:Calcium / Q000494:pharmacology; D002942:Circular Dichroism; D004735:Energy Transfer; D044949:Kaempferols / Q000378:metabolism* / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D008958:Models, Molecular; D017433:Protein Structure, Secondary / Q000187:drug effects; D013050:Spectrometry, Fluorescence
D065095:Calcineurin Inhibitors; D044949:Kaempferols; D008345:Manganese; C006552:kaempferol; D019703:Calcineurin; D002118:Calcium