Multispectroscopic binding studies and in silico docking analysis of interactions of malic acid with xanthine oxidase

•Study sought to determine binding ability of malic acid with XO.•Multispectroscopic binding analysis and in silico docking studies were carried out.•Malic acid have the capability to alter the structural activity of XO.•These findings support the development of a new lead molecule for XO inhibition. Malic acid, an organic dicarboxylic acid found primarily in plants and fruits, has a wide range of functions and uses. Using various spectroscopic approaches and in silico docking studies, the binding potential of malic acid with Xanthine oxidase (XO) was investigated. XO is a four chained homodimer metalloflavoprotein having a molecular weight of 290 kDa. Each sub unit contains a pair of ion sulfur centres [2Fe-2S] and a FAD center. The molybdenum center regulates the catalytic activity of XO. XO generates superoxide by catalysing the conversion of hypoxanthine and xanthine to uric acid. Many major clinical issues are caused by an excess of uric acid and superoxide anion radical in the body. The activity and structural changes of XO can be an effective way to lower these associated risk factors. The fluorescence titration data revealed interactions of malic acid with XO started by a static quenching mechanism. The spectroscopic investigation of malic acid bind with XO using ultraviolet (UV), fourier-transform infrared (FTIR), and circular dichroism (CD) revealed a secondary structural change in XO. Docking studies showed molecular level interaction of malic acid with the amino acid residues of Leu 1014, Ser 876, Leu 873, Arg 880, Phe 914, Thr 1010, Phe1009, Ala 1079, Ser 1008, Val 1011, Glu 802 which residing at the catalytic active site of the XO. These results imply that malic acid has a remarkable interaction with XO. These findings support the XO inhibition research and the development of a new lead molecule.