Publication: Metal organik kafes tabanlı polimerik film hazırlanması ve fisin enzim uygulamaları
Abstract
Bu çalışmada, incir ağaçlarının lateksinden ekstrakte edilen proteaz aktivitesinin yanı sıra, içsel peroksidaz benzeri aktiviteye sahip bir sistein proteolitik enzimi olan fisin, zeolitik imidazolat çerçevesi-8 (ZIF8)-Kitosan ve Kitosan filmlerine immobilize edildi. Kitosan ve ZIF8-Kitosan filme sırasıyla gram polimere 0,486 mg ve 0,666 mg enzim bağlandığı ve enzim bağlanma yüzdeleri 61,7 ve 72,5 şeklinde bulundu. Fisin, yükleme kapasitesi nedeniyle ZIF8-Kitosan filmine özellikle daha iyi immobilize olmuştur. Serbest fisin pH 7 ve 60 °C'de maksimum aktivite gösterirken, immobilize Kitosan-Enzim pH 8 ve 80°C ve ZIF8-Kitosan-Enzim pH 6 ve 80°C’de maksimum aktivite göstermişlerdir. İmmobilize enzimlerin termal stabilitelerinin arttığı görülmektedir. İmmobilize enzimlerin Vmaks değerleri, serbest formunkinden daha düşük, Km değerleri ise daha yüksek tayin edilmiştir. Endüstriyel uygulamalarda enzimlerin geri kazanılması ve yeniden kullanılabilirliği başarılı operasyonlar için anahtar faktörlerden biridir. Birbirini takip eden 15 tekrardan sonra immobilize Kitosan-Enzim ve ZIF8-Kitosan-Enzim başlangıç aktivitelerini yaklaşık %50 ve 55 oranında korumuştur. Serbest fisinin, Kitosan-Enzim ve ZIF8-Kitosan-Enzim üzerinde 60 günlük bir süre boyunca depolama stabilitesi incelendiğinde yaklaşık %30, %14 ve %10 aktivite kaybı gösterdikleri bulunmuştur.
In this study, ficin, a cysteine proteolytic enzyme with intrinsic peroxidase-like activity, as well as protease activity extracted from the latex of fig trees, was immobilized into zeolitic imidazolate framework-8 (ZIF8)-Chitosan and Chitosan films. It was found that 0.486 mg and 0.666 mg of enzyme were bound to Chitosan and ZIF8-Chitosan film per gram of polymer, respectively, and the enzyme binding percentages were 61.7 and 72.5. Ficin was particularly better immobilized to the ZIF8-Chitosan film due to its loading capacity. While free ficin showed maximum activity at pH 7 and 60 °C, immobilized Chitosan-Enzyme showed maximum activity at pH 8 and 80 °C and ZIF8-Chitosan-Enzyme showed maximum activity at pH 6 and 80 °C. It appears that the thermal stability of immobilized enzymes increases. Vmax values of immobilized enzymes were determined to be lower than those of the free form, and Km values were determined to be higher. In industrial applications, the recovery and reusability of enzymes is one of the key factors for successful operations. After 15 consecutive repetitions, immobilized Chitosan-Enzyme and ZIF8-Chitosan-Enzyme retained their initial activities at approximately 50 and 55%. When the storage stability of free ficin on Chitosan-Enzyme and ZIF8-Chitosan-Enzyme was examined over a period of 60 days, it was found that they showed approximately 30%, 14% and 10% loss of activity.
In this study, ficin, a cysteine proteolytic enzyme with intrinsic peroxidase-like activity, as well as protease activity extracted from the latex of fig trees, was immobilized into zeolitic imidazolate framework-8 (ZIF8)-Chitosan and Chitosan films. It was found that 0.486 mg and 0.666 mg of enzyme were bound to Chitosan and ZIF8-Chitosan film per gram of polymer, respectively, and the enzyme binding percentages were 61.7 and 72.5. Ficin was particularly better immobilized to the ZIF8-Chitosan film due to its loading capacity. While free ficin showed maximum activity at pH 7 and 60 °C, immobilized Chitosan-Enzyme showed maximum activity at pH 8 and 80 °C and ZIF8-Chitosan-Enzyme showed maximum activity at pH 6 and 80 °C. It appears that the thermal stability of immobilized enzymes increases. Vmax values of immobilized enzymes were determined to be lower than those of the free form, and Km values were determined to be higher. In industrial applications, the recovery and reusability of enzymes is one of the key factors for successful operations. After 15 consecutive repetitions, immobilized Chitosan-Enzyme and ZIF8-Chitosan-Enzyme retained their initial activities at approximately 50 and 55%. When the storage stability of free ficin on Chitosan-Enzyme and ZIF8-Chitosan-Enzyme was examined over a period of 60 days, it was found that they showed approximately 30%, 14% and 10% loss of activity.