title: Inhibition of catalase by tea catechins in free and cellular state: a biophysical approach.
abstract: Tea flavonoids bind to variety of enzymes and inhibit their activities. In the present study, binding and inhibition of catalase activity by catechins with respect to their structure-affinity relationship has been elucidated. Fluorimetrically determined binding constants for (-)-epigallocatechin gallate (EGCG) and (-)-epicatechin gallate (ECG) with catalase were observed to be 2.27×106 M(-1) and 1.66×106 M(-1), respectively. Thermodynamic parameters evidence exothermic and spontaneous interaction between catechins and catalase. Major forces of interaction are suggested to be through hydrogen bonding along with electrostatic contributions and conformational changes. Distinct loss of α-helical structure of catalase by interaction with EGCG was captured in circular dichroism (CD) spectra. Gallated catechins demonstrated higher binding constants and inhibition efficacy than non-gallated catechins. EGCG exhibited maximum inhibition of pure catalase. It also inhibited cellular catalase in K562 cancer cells with significant increase in cellular ROS and suppression of cell viability (IC50 54.5 µM). These results decipher the molecular mechanism by which tea catechins interact with catalase and highlight the potential of gallated catechin like EGCG as an anticancer drug. EGCG may have other non-specific targets in the cell, but its anticancer property is mainly defined by ROS accumulation due to catalase inhibition.
authors.affiliation: Department of Biotechnology, West Bengal University of Technology, Kolkata, West Bengal, India.
authors.forename: Sandip
authors.initials: S
authors.lastname: Pal
authors.affiliation: Department of Biotechnology, West Bengal University of Technology, Kolkata, West Bengal, India.
authors.forename: Subrata Kumar
authors.initials: SK
authors.lastname: Dey
authors.affiliation: Department of Biotechnology, West Bengal University of Technology, Kolkata, West Bengal, India.
authors.forename: Chabita
authors.initials: C
authors.lastname: Saha
mesh_terms: D002374:Catalase / Q000037:antagonists & inhibitors* / Q000737:chemistry; D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D004353:Drug Evaluation, Preclinical; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D020128:Inhibitory Concentration 50; D020014:K562 Cells; D011485:Protein Binding; D013662:Tea / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D013662:Tea; D002392:Catechin; C062669:epicatechin gallate; D006861:Hydrogen Peroxide; C045651:epigallocatechin gallate; D002374:Catalase