Publication: Hidroliz ve sentez reaksiyonlarında biyokatalizör olarak mof tabanlı polimerik filmlere lipaz immobilizasyonu
Abstract
Enzimler reaksiyon hızını arttıran doğal biyokatalizörlerdir. Bununla birlikte enzimler yeniden kullanım zorluğu ve maliyetli üretim süreci gibi bazı dezavantajlara sahiptir. Bu dezavantajların giderilmesi için enzim immobilizasyonu sıklıkla kullanılan tekniklerden biridir. Enzim katı bir destek yüzeyine sabitlenerek yeniden kullanımları sağlanmakta ayrıca enzimlerin çeşitli koşullara dayanımı arttırılabilmektedir. Serin hidrolaz sınıfından olan lipazlar hem hidroliz hem de sentez reaksiyonlarını katalizleyebilen çok yönlü enzimlerdir. Hayvansal, bitkisel ve mikrobiyal kaynaklardan elde edilebilirler. Stabilitesi yüksek olan ve farklı konsantrasyonlarda çalışabilen lipazlar endüstride önemli bir konumdadır. Gıda, ilaç, tekstil, kozmetik, biyodizel üretimi gibi pek çok farklı alanda değerlendirilirler. Bu çalışmada Candida rugosa lipazı, amin modifiye ZIF8 (ZIF8-NH2) içeren ve içermeyen UV ile kürlenebilen polimerik destek materyaline immobilize edildi. 1 g polimere bağlanan enzim miktarı ZIF8-NH2 içermeyen film ve %1, %3 ve %5 oranında ZIF8-NH2 içeren filmlere sırayla 2,34 mg, 3,12 mg, 3,20 mg ve 3,59 mg olarak bulundu. İmmobilize ve serbest enzimlerin su ortamında p-nitrofenil palmitatın hidrolizi ve n-heksan ortamında p-nitrofenil palmitatın sentezi(p-nitrofenol ve palmitik asit) olmak üzere iki farklı reaksiyon ortamında aktivite tayinleri incelendi. Serbest enzime kıyasla, immobilize enzimin yükselen pH ve sıcaklık değerlerinde aktivitesini daha iyi koruduğu gözlemlendi. Hidrolitik ve sentetik aktivite tayin yöntemine göre ZIF8-NH2 içermeyen film ve %1, %3 ve %5 oranında ZIF8-NH2 içeren filmlerde 6 tekrar kullanımdan sonra sırayla yaklaşık yüzde %67-70 ve %83-87 oranında aktivitelerini korudukları tayin edildi. Doğal enzimin 30 gün sonunda %60 oranında aktivitesini kaybettiği, aynı depolama süresi altında hidrolitik ve sentetik aktiviteleri için immobilize enzimlerin sırasıyla yaklaşık %72-77 ve %74-80 oranında aktivitesini koruduğu tayin edildi.
Enzymes are natural biocatalysts that increase reaction rates. However, enzymes have some disadvantages such as difficulty in reuse and the costly production process. Enzyme immobilization is one of the frequently used techniques to overcome these disadvantages. Enzymes are fixed to a solid support surface and their reuse is ensured, and their resistance to various conditions can be increased. Lipases, which belong to the serine hydrolase class, are versatile enzymes that can catalyze both hydrolysis and synthesis reactions. They can be obtained from animal, plant and microbial sources. Lipases with high stability and that can work at different concentrations are in an important position in the industry. They are evaluated in many different areas such as food, medicine, textile, cosmetics, and biodiesel production. In this study, Candida rugosa lipase was immobilized on UV-curable polymeric support material containing and not containing amine modified ZIF8 (ZIF8-NH2). The amount of enzyme bound to 1 g of polymer was found to be 2.34 mg for the film without ZIF8-NH2, and 3.12 mg, 3.20 mg, and 3.59 mg for the films containing 1%, 3%, and 5% ZIF8-NH2, respectively. The activities of immobilized and free enzymes were investigated in two different reaction systems: hydrolysis of p-nitrophenyl palmitate in aqueous medium and synthesis of p nitrophenyl palmitate (from p-nitrophenol and palmitic acid) in n-hexane medium. It was observed that the immobilized enzyme maintained its activity better at increasing pH and temperature values compared to the free enzyme. According to the hydrolytic and synthetic activity determination method, it was determined that the films without ZIF8-NH2 and the films containing 1%, 3% and 5% ZIF8-NH2 retained their activities by approximately 67-70% and 83-87% after 6 reuses, respectively. It was determined that the free enzyme lost 60% of its activity after 30 days, and the immobilized enzymes retained their activities by approximately 72-77% and 74-80%, respectively, for hydrolytic and synthetic activities under the same storage period.
Enzymes are natural biocatalysts that increase reaction rates. However, enzymes have some disadvantages such as difficulty in reuse and the costly production process. Enzyme immobilization is one of the frequently used techniques to overcome these disadvantages. Enzymes are fixed to a solid support surface and their reuse is ensured, and their resistance to various conditions can be increased. Lipases, which belong to the serine hydrolase class, are versatile enzymes that can catalyze both hydrolysis and synthesis reactions. They can be obtained from animal, plant and microbial sources. Lipases with high stability and that can work at different concentrations are in an important position in the industry. They are evaluated in many different areas such as food, medicine, textile, cosmetics, and biodiesel production. In this study, Candida rugosa lipase was immobilized on UV-curable polymeric support material containing and not containing amine modified ZIF8 (ZIF8-NH2). The amount of enzyme bound to 1 g of polymer was found to be 2.34 mg for the film without ZIF8-NH2, and 3.12 mg, 3.20 mg, and 3.59 mg for the films containing 1%, 3%, and 5% ZIF8-NH2, respectively. The activities of immobilized and free enzymes were investigated in two different reaction systems: hydrolysis of p-nitrophenyl palmitate in aqueous medium and synthesis of p nitrophenyl palmitate (from p-nitrophenol and palmitic acid) in n-hexane medium. It was observed that the immobilized enzyme maintained its activity better at increasing pH and temperature values compared to the free enzyme. According to the hydrolytic and synthetic activity determination method, it was determined that the films without ZIF8-NH2 and the films containing 1%, 3% and 5% ZIF8-NH2 retained their activities by approximately 67-70% and 83-87% after 6 reuses, respectively. It was determined that the free enzyme lost 60% of its activity after 30 days, and the immobilized enzymes retained their activities by approximately 72-77% and 74-80%, respectively, for hydrolytic and synthetic activities under the same storage period.