title: Correlation of lysozyme activity and stability in the presence of Hofmeister series anions.
abstract: Enzymatic activity and stability of lysozyme in the presence of salts have been studied by fluorescence spectroscopy and differential scanning calorimetry, respectively. The effect of sodium salts of sulfate, acetate, chloride, bromide, thiocyanate, and perchlorate on lysozyme properties depends on anion concentration as well as on position of anion in the Hofmeister series. Kosmotropic anions (sulfate and acetate) increase stability and activate the enzyme while chaotropic anions (bromide, thiocyanate and perchlorate) including chloride decrease stability and inhibits the enzyme activity. Strong correlation between stability and activity of lysozyme suggest the interdependence of these enzyme properties in the presence of salts. The fact that the properties of lysozyme correlate with partition coefficients of anions at hydrocarbon surface clearly indicates that Hofmeister effect of anions is mediated by their interactions with nonpolar parts of the enzyme surface despite its high positive net charge at studied conditions. The efficiency of the anions in affecting both activity and stability of lysozyme also correlates with other anion-related parameters most notably with polarizability of monovalent anions. The presented work points to a critical role of interaction of anions with nonpolar protein surface for the Hofmeister effect. Moreover, the simultaneous investigation of protein stability and activity, in the relation with the Hofmeister effect, provides important information regarding stability/rigidity of enzyme structure for its catalytic activity.
authors.affiliation: Department of Biochemistry, Faculty of Science, P. J. Šafárik University in Košice, Moyzesova 11, 04001 Košice, Slovakia.
authors.forename: Katarína
authors.initials: K
authors.lastname: Garajová
authors.affiliation: Department of Biochemistry, Faculty of Science, P. J. Šafárik University in Košice, Moyzesova 11, 04001 Košice, Slovakia.
authors.forename: Anna
authors.initials: A
authors.lastname: Balogová
authors.affiliation: Department of Biophysics, Faculty of Science, P. J. Šafárik University in Košice, Jesenná 5, 04001 Košice, Slovakia.
authors.forename: Eva
authors.initials: E
authors.lastname: Dušeková
authors.affiliation: Department of Biophysics, Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 04001 Košice, Slovakia.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Sedláková
authors.affiliation: Department of Biochemistry, Faculty of Science, P. J. Šafárik University in Košice, Moyzesova 11, 04001 Košice, Slovakia; Centre for Interdisciplinary Biosciences, P. J. Šafárik University in Košice, Jesenná 5, 04001 Košice, Slovakia.
authors.forename: Erik
authors.initials: E
authors.lastname: Sedlák
authors.affiliation: Department of Biochemistry, Faculty of Science, P. J. Šafárik University in Košice, Moyzesova 11, 04001 Košice, Slovakia. Electronic address: rastislav.varhac@upjs.sk.
authors.forename: Rastislav
authors.initials: R
authors.lastname: Varhač
mesh_terms: D000818:Animals; D000838:Anions / Q000737:chemistry* / Q000378:metabolism*; D002645:Chickens / Q000378:metabolism; D004531:Eggs; D009113:Muramidase / Q000737:chemistry* / Q000378:metabolism*; D055550:Protein Stability; D012492:Salts / Q000737:chemistry / Q000378:metabolism
chemical_list: D000838:Anions; D012492:Salts; D009113:Muramidase
keywords: Hofmeister series anions; Lysozyme; Partition coefficient; Specific activity; Thermal stability