title: Modified β-casein restores thermal reversibility of human carbonic anhydrase II: the salt bridge mechanism.
abstract: Modified β-casein (mβ-CN) was investigated as an efficient additive for thermal reversibility of human carbonic anhydrase II (HCA II) at pH 7.75. The mβ-CN was obtained via modification of β-casein (β-CN) acidic residues using Woodward's reagent K. The effects of mβ-CN on the reversibility and stability of HCA II were determined by differential scanning calorimetry, UV-vis, and 1-anilinonaphthalene-8-sulfonic acid fluorescence spectroscopic methods. The mβ-CN, as an additive, enhanced thermal reversibility of HCA II by 33%. Together, our results indicated that mβ-CN is very efficient in decreasing thermal aggregation and enhancing the stability of HCA II. Using theoretical studies, we propose that the mechanism for thermal reversibility is mediated through formation of a salt bridge between the Woodward part of mβ-CN and the Zn ion of HCA II.
authors.affiliation: Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
authors.forename: Azadeh
authors.initials: A
authors.lastname: Fallah-Bagheri
authors.forename: Ali Akbar
authors.initials: AA
authors.lastname: Moosavi-Movahedi
authors.forename: Mohammad
authors.initials: M
authors.lastname: Taghizadeh
authors.forename: Reza
authors.initials: R
authors.lastname: Khodarahmi
authors.forename: Leila
authors.initials: L
authors.lastname: Ma'mani
authors.forename: Nooshin
authors.initials: N
authors.lastname: Bijari
authors.forename: Mousa
authors.initials: M
authors.lastname: Bohlooli
authors.forename: Abbas
authors.initials: A
authors.lastname: Shafiee
authors.forename: Nader
authors.initials: N
authors.lastname: Sheibani
authors.forename: Ali Akbar
authors.initials: AA
authors.lastname: Saboury
mesh_terms: D002152:Calorimetry, Differential Scanning / Q000379:methods; D024402:Carbonic Anhydrase II / Q000737:chemistry* / Q000378:metabolism*; D002364:Caseins / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D055550:Protein Stability; D012492:Salts / Q000737:chemistry* / Q000378:metabolism*; D013050:Spectrometry, Fluorescence / Q000379:methods; D013329:Structure-Activity Relationship
chemical_list: D002364:Caseins; D012492:Salts; D024402:Carbonic Anhydrase II