Characteristics of immobilized urease onto modified zirconium (IV) oxide via glutaraldehyde: kinetic, stability, and operational stabilities in bioreactors

Alptekin Ö.

CHEMICAL PAPERS, cilt.76, sa.2, ss.749-761, 2022 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 76 Sayı: 2
  • Basım Tarihi: 2022
  • Doi Numarası: 10.1007/s11696-021-01891-6
  • Dergi Adı: CHEMICAL PAPERS
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core
  • Sayfa Sayıları: ss.749-761
  • Anahtar Kelimeler: Urease, Immobilization, Zirconium (IV) oxide, Operational stability, Bioreactors, JACK BEAN UREASE, THERMAL INACTIVATION, STORAGE STABILITY, CATALASE, SURFACE, MEMBRANE
  • Çukurova Üniversitesi Adresli: Evet

Özet

This study aimed to obtain an efficient immobilized urease covalently immobilized onto modified zirconium (IV) oxide (ZrO2) that could serve in a dialysate regeneration system. For the first time, the characteristics of modified ZrO2 and immobilized urease preparations were studied in detail. The operational stabilities of urease in batch and continuous flow-type reactors were also compared. ZrO2 was sequentially modified with Piranha, 3-aminopropyl triethoxysilane, and glutaraldehyde (GA) followed by urease immobilization. The surface area of the carrier was increased by 29% after Piranha treatment. The bound urease onto modified ZrO2 was 3.9 mg g carrier(-1). Optimum pH and temperature of free and immobilized ureases were found as 6.5 and 50 degrees C, and 7.0 and 60 degrees C, respectively. Following immobilization, the K-m value of urease was increased from 2.7 +/- 0.1 to 10.2 +/- 0.4 mM and the V-max value decreased from 51.6 +/- 2.0 to 0.16 + 0.02 U mg protein(-1). The immobilized urease was 62, 35, and 46 fold more stable than the free urease at 50, 60, and 70 degrees C, respectively. It showed 90 and 58% of its initial activity at 4 degrees C and room temperature at the end of 12 days, respectively. The amount of removed urea was found to be 0.22 mg in a batch-type reactor and 0.39 mg in a continuous flow-type reactor at the end of 60 min. The immobilized urease onto ZrO2 has superior potential to use in artificial kidney machines due to significant contribution to reducing device weight.