title: Investigation on the surface hydrophobicity and aggregation kinetics of human calprotectin in the presence of calcium.
abstract: Calcium and zinc binding protein, calprotectin is a multifunctional protein with broad spectrum antimicrobial and antitumoural activity. It was purified from human neutrophil, using a two-step ion exchange chromatography. Since surface hydrophobicity of calprotectin may be important in membrane anchoring, membrane penetration, subunits oligomerization and some biological roles of protein, in this study attempted to explore the effect of calcium in physiological range on the calprotectin lipophilicity. Incubation of human calprotectin (50 microg/ml) with different calcium concentrations showed that 1-anilino-8-naphthalene sulfonic acid (ANS) fluorescence intensity of the protein significantly elevates with calcium in a dose dependent manner, suggesting an increase in calprotectin surface hydrophobicity upon calcium binding. Our study also indicates that calcium at higher concentrations (6, 8 and 10 mM) induces aggregation of human calprotectin. Our finding demonstrates that the starting time and the rate constant of calprotectin aggregation depend on the calcium concentration.
authors.affiliation: Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Yousefi
authors.forename: Susan K
authors.initials: SK
authors.lastname: Ardestani
authors.forename: Ali Akbar
authors.initials: AA
authors.lastname: Saboury
authors.forename: Amina
authors.initials: A
authors.lastname: Kariminia
authors.forename: Madjid
authors.initials: M
authors.lastname: Zeinali
authors.forename: Mojtaba
authors.initials: M
authors.lastname: Amani
mesh_terms: D000817:Anilino Naphthalenesulfonates / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D005453:Fluorescence; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D039841:Leukocyte L1 Antigen Complex / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D000817:Anilino Naphthalenesulfonates; D039841:Leukocyte L1 Antigen Complex; C027132:1-anilino-8-naphthalenesulfonate; D002118:Calcium