Effect of ionic environments on the adsorption and diffusion characteristics of serine alkaline protease enzyme in polyethersulfone ultrafiltration membranes

Salgin S., Takac S., Ozdamar T. H.

JOURNAL OF COLLOID AND INTERFACE SCIENCE, cilt.299, sa.2, ss.806-814, 2006 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 299 Sayı: 2
  • Basım Tarihi: 2006
  • Doi Numarası: 10.1016/j.jcis.2006.03.020
  • Dergi Adı: JOURNAL OF COLLOID AND INTERFACE SCIENCE
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.806-814
  • Anahtar Kelimeler: adsorption, diffusion coefficient, protease, hofmeister series, BOVINE SERUM-ALBUMIN, POROUS POLYETHYLENE MEMBRANE, TRANSPORT, PH, AGGREGATION, COEFFICIENT, MECHANISM, ACID, BSA
  • Ankara Üniversitesi Adresli: Evet

Özet

Static adsorption of serine alkaline protease (SAP) enzyme on hydrophobic polyether sulfone (PES) ultrafiltration membranes in different ionic environments was investigated. The amount of SAP adsorbed on membranes was the lowest at its isoelectric point (IEP) where the maximum adsorption was obtained below the IEP of the enzyme. The extent of SAP adsorption in the phosphate buffer solutions including different salts followed the order: (NH4)(2)HPO4 > KH2PO4 > Na2HPO4-NaH2PO4 (buffer) > CaCl2 > ((NH4)(2)HPO4 + H2PO4 + CaCl2), which was consistent with the Hofmeister series. The zeta potentials of membranes contacted with the ionic species were calculated by streaming potential measurements and found that the increase in ionic strength decreased the electrical double layer thickness leading to a decrease in adsorption. A model based on mass balance was developed to calculate the diffusion coefficient of SAP in PES membranes. Employing experimental data evaluated in a diffusion cell along with the data of adsorption isotherms, diffusion coefficients of SAP in PES membranes in the presence of different ionic species were calculated. To detect the structural changes occurred, membrane surfaces were analysed by Fourier transform infrared-attenuated total reflectance (FTIR-ATR) measurements. (c) 2006 Elsevier Inc. All rights reserved.