Author(s): Fallah-Bagheri A, Moosavi-Movahedi AA, Taghizadeh M, Khodarahmi R, Ma’mani L, Bijari N, Bohlooli M, Shafiee A, Sheibani N, Saboury AA. Modified β-casein restores thermal reversibility of human carbonic anhydrase II: the salt bridge mechanism. Biotechnol Appl Biochem. 2013 May-Jun;60(3):298-304. doi: 10.1002/bab.1081. Epub 2013 Apr 28. PMID 23621563
Journal: Biotechnology And Applied Biochemistry, Volume 60, Issue 3, 2013
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.