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Abstract

Human serum albumin (HSA) is an important plasma protein responsible for the binding and transport of many endogenous and exogenous substances including hormones, fatty acids and foreign molecules such as drugs. Most of the drugs can bind to HSA and be transported to target locations of the body. For this study, Trimethoxy flavone (TMF) is used which is a naturally occurring flavone isolated from Andrographisviscosula and used in the treatment of dyspepsia, influenza, malaria, respiratory functions and as a astringent and antidote for poisonous stings of some insects. In order to see the binding, conformation and binding sites of the HSA-TMF complexation we used fluorescence emission, mass spectrometry, circular dichroism and molecular docking parameters. The fluorescence emission was quenched and the binding constant of TMF with HSA was found to be K TMF =1.0 + 0.01 x 103 M -1 , which corresponds to -5.4 kcal M -1 of free energy. Micro-TOF Q results showed a mass increase of from 65,117 Da (free HSA) to 66,689 Da (HSA +Drug), indicating the strong binding of TMF with HSA resulting in decrease of fluorescence. The HSA conformation was altered upon binding of TMF to HSA with decrease α-helix and an increase in β-sheets and random coils suggesting partial unfolding of protein secondary structure. Molecular docking experiments found that TMF binds strongly with HSA at IIIA domain of hydrophobic pocket with hydrogen bond and hydrophobic interactions. Among which two hydrogen bonds are formed between O (19) of TMF to Arg 410, Tyr 411 and another one from O (7) of TMF to Asn 391, with bond distance of 2.1Å, 3.6Å and 2.6Å, respectively. In view of the evidence presented, it is imperative to assign a greater role of HSA?s as a carrier molecule for many drugs to understand the interactions of HSA with TMF will be pivotal in the design of new TMF-inspired drugs.

Biography

G. Mahesh completed his M.Sc in Biochemistry in the year 2005 from University of Hyderabad, Hyderabad, Andhra Pradesh, after pursuing his master?s degree, he joined as a JRF under Dr. S. Rajagopal, Reader, Department of Plant sciences. Now he is pursuing his Ph.D under the same supervisor in the field of Biochemistry. In the past four years he has published 5 papers in reputed international journals (Plos one, Journal of photobiology and photochemistry B, The Journal of physical Chemistry B, Journal of Molecular modeling).