Investigations on the interaction of the phototoxic alkaloid coralyne with serum albumins.
The interaction of the phototoxic alkaloid coralyne with bovine and human serum albumins (BSA, HSA) was investigated. Absorbance and fluorescence quenching experiments revealed the formation of strong complexes. Based on the binding parameters calculated from Stern-Volmer quenching method, coralyne has higher affinity to BSA (~10(5) M(-1)) compared to HSA (~10(4) M(-1)). Forster resonance energy transfer studies showed that the specific binding distances between Trp (donor) of the proteins and coralyne (acceptor) were 2.95 and 3.10 nm, respectively. The bindings were favored by negative enthalpy and a stronger favorable entropy contribution. The heat capacity values for binding to BSA and HSA were similar, indicating the involvement of similar molecular forces in the complexation. Competitive binding experiments using site markers demonstrated that coralyne binds to site I (subdomain IIA) of both proteins. The secondary structure of the proteins was altered, suggesting a small but definitive partial unfolding on complexation.
Biophysical Chemistry Laboratory, CSIR-Indian Institute of Chemical Biology, Kolkata 700 032, India.
Asma Yasmeen
AY
Khan
Maidul
M
Hossain
Gopinatha
G
Suresh Kumar
D000818:Animals; D001600:Berberine Alkaloids / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity; D002417:Cattle; D031541:Fluorescence Resonance Energy Transfer; D015386:Hazardous Substances / Q000378:metabolism*; D006801:Humans; D055668:Photochemical Processes; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism*; D012710:Serum Albumin, Bovine / Q000737:chemistry / Q000378:metabolism*
D001600:Berberine Alkaloids; D015386:Hazardous Substances; D012709:Serum Albumin; D012710:Serum Albumin, Bovine; C000666:coralyne