title: Comparative study of the binding of pepsin to four alkaloids by spectrofluorimetry.
abstract: The interactions between pepsin and four alkaloids, including caffeine (Caf), aminophylline (Ami), acefylline (Ace), diprophylline (Dip), were investigated by fluorescence, UV-visible absorption, resonance light scattering, synchronous fluorescence spectroscopy and 3D spectroscopy under mimic physiological conditions. The results revealed that Caf (Ami/Ace/Dip) caused the fluorescence quenching of pepsin by the formation of Caf (Ami/Ace/Dip)-pepsin complex. The binding constants and thermodynamic parameters at three different temperatures, the binding locality and the binding power were obtained. The hydrophobic and electrostatic interactions were the predominant intermolecular forces to stabilize the complex. Results showed that aminophylline was the stronger quencher and bound to pepsin with higher affinity than other three alkaloids.
authors: Department of Chemistry, Zhengzhou University, Zhengzhou 450001, China. wangry@zzu.edu.cn
authors: Ruiyong
authors: R
authors: Wang
authors: Yuanzhe
authors: Y
authors: Xie
authors: Yuhai
authors: Y
authors: Zhang
authors: Xiaohui
authors: X
authors: Kang
authors: Xiaogai
authors: X
authors: Wang
authors: Baoyu
authors: B
authors: Ge
authors: Junbiao
authors: J
authors: Chang
mesh_terms: D000042:Absorption; D000470:Alkaloids / Q000737:chemistry / Q000378:metabolism*; D000628:Aminophylline / Q000737:chemistry / Q000378:metabolism; D002110:Caffeine / Q000737:chemistry / Q000378:metabolism; D004400:Dyphylline / Q000737:chemistry / Q000378:metabolism; D004735:Energy Transfer; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008027:Light; D010434:Pepsin A / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D012542:Scattering, Radiation; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature; D013806:Theophylline / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism
chemical_list: D000470:Alkaloids; D004400:Dyphylline; D000628:Aminophylline; D002110:Caffeine; D013806:Theophylline; D010434:Pepsin A; C019140:acefylline