title: Unravelling the binding mechanism and protein stability of human serum albumin while interacting with nefopam analogues: a biophysical and insilico approach.
abstract: In this study, molecular binding affinity was investigated for Nefopam analogues (NFs), a functionalized benzoxazocine, with human serum albumin (HSA), a major transport protein in the blood. Its binding affinity and concomitant changes in its conformation, binding site and simulations were also studied. Fluorescence data revealed that the fluorescence quenching of HSA upon binding of NFs analogues is based on a static mechanism. The three analogues of NFs binding constants (KA) are in the order of NF3 > NF2 > NF1 with values of 1.53 ± .057 × 104, 2.16 ± .071 × 104and 3.6 ± .102 × 105M-1, respectively. Concurrently, thermodynamic parameters indicate that the binding process was spontaneous, and the complexes were stabilized mostly by hydrophobic interactions, except for NF2 has one hydrogen bond stabilizes it along with hydrophobic interactions. Circular dichroism (CD) studies revealed that there is a decrease in α-helix with an increase in β-sheets and random coils signifying partial unfolding of the protein upon binding of NFs, which might be due to the formation of NFs-HSA complexes. Further, molecular docking studies showed that NF1, NF2 and NF3 bound to subdomains IIIA, IB and IIA through hydrophobic interactions. However, NF1 have additionally formed a single hydrogen bond with LYS 413. Furthermore, molecular simulations unveiled that NFs binding was in support with the structural perturbation observed in CD, which is evident from the root mean square deviation and Rgfluctuations. We hope our insights will provide ample scope for engineering new drugs based on the resemblances with NFs for enhanced efficacy with HSA.
authors.affiliation: a Department of Biochemistry , School of Life Sciences, University of Hyderabad , Hyderabad 500046 , India.
authors.forename: Mahesh
authors.initials: M
authors.lastname: Gokara
authors.affiliation: b School of Chemistry , University of Hyderabad , Hyderabad 500046 , India.
authors.forename: Vidadala V
authors.initials: VV
authors.lastname: Narayana
authors.affiliation: a Department of Biochemistry , School of Life Sciences, University of Hyderabad , Hyderabad 500046 , India.
authors.forename: Vineet
authors.initials: V
authors.lastname: Sadarangani
authors.affiliation: a Department of Biochemistry , School of Life Sciences, University of Hyderabad , Hyderabad 500046 , India.
authors.forename: Shatabdi Roy
authors.initials: SR
authors.lastname: Chowdhury
authors.affiliation: a Department of Biochemistry , School of Life Sciences, University of Hyderabad , Hyderabad 500046 , India.
authors.forename: Sreelaxmi
authors.initials: S
authors.lastname: Varkala
authors.affiliation: b School of Chemistry , University of Hyderabad , Hyderabad 500046 , India.
authors.forename: Dhevalapally B
authors.initials: DB
authors.lastname: Ramachary
authors.affiliation: c Department of Plant Sciences , School of Life Sciences, University of Hyderabad , Hyderabad 500046 , India.
authors.forename: Rajagopal
authors.initials: R
authors.lastname: Subramanyam
mesh_terms: D018712:Analgesics, Non-Narcotic / Q000737:chemistry*; D001665:Binding Sites; D001667:Binding, Competitive; D006801:Humans; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D007052:Ibuprofen / Q000737:chemistry*; D007700:Kinetics; D008012:Lidocaine / Q000737:chemistry*; D062105:Molecular Docking Simulation; D056004:Molecular Dynamics Simulation; D009340:Nefopam / Q000031:analogs & derivatives / Q000737:chemistry*; D010653:Phenylbutazone / Q000737:chemistry*; D011485:Protein Binding; D000072756:Protein Conformation, alpha-Helical; D000072757:Protein Conformation, beta-Strand; D054730:Protein Interaction Domains and Motifs; D055550:Protein Stability; D000075462:Serum Albumin, Human / Q000737:chemistry*; D012996:Solutions; D013816:Thermodynamics
chemical_list: D018712:Analgesics, Non-Narcotic; D012996:Solutions; D009340:Nefopam; D008012:Lidocaine; D010653:Phenylbutazone; D007052:Ibuprofen; D000075462:Serum Albumin, Human
keywords: Human serum albumin; binding studies; docking studies; nefopam; protein stability