EOZİN İLE GLUTATYON TRANSFERAZ TAU45’İN İNHİBİSYONU

Öz

Amaç: Glutatyon transferazlar (GST), canlı sistemlerde glutatyonu elektrofilik bileşiklerle katalize eden çok işlevli enzimlerdir. Bitkilerde tau (GSTU) sınıfı, kavak ağaçlarında (Populus trichocarpa) 81 alt birim ile en geniş sınıfı oluşturmaktadır. Bitki GST'lerinin işlevleri ve inhibitörleri üzerine yapılan çalışmalar büyük ölçüde keşfedilmemiş durumdadır. Bu çalışma, eozinin Populus trichocarpa GSTU45 üzerindeki inhibitör etkisini araştırmaktadır. GST inhibitörleri, yabancı otlarda ortaya çıkan herbisit direncinin aşılması ve bitki koruma stratejilerinin etkinliğinin artırılması gibi tarımsal biyoteknoloji uygulamalarında kullanılabilir.

Gereç ve Yöntem: Enzim, Escherichia coli'de heterolog olarak eksprese edildi ve nikel sefaroz afinite kromatografisi ile saflaştırıldı. Eozinin poplar GSTU45 üzerindeki inhibisyon etkisi, 1-kloro-2,4-dinitrobenzen (CDNB) substratı kullanılarak spektrofotometrik yöntemle incelendi.

Sonuç ve Tartışma: Eozin, en yaygın kullanılan substrat olan CDNB ile 11.0 ± 1.0 µM IC₅₀ değeri ile orta düzeyde bir inhibitördür. İnhibisyon kinetiği analizleri, glutatyona (GSH) karşı karışık tip inhibisyon (K_i = 3.3 ± 0.4 µM) ve CDNB'ye karşı kompetitif inhibisyon (K_i = 1.9 ± 0.1 µM) gösterdiğini saptadı. Bu bulgular, eozinin hem G-bölgesi hem de H-bölgesine bağlandığını göstermektedir. Elde edilen sonuçlar, tau GST'lerinin inhibisyon mekanizmasına yeni bilgiler sunmakta olup, bu enzimlerin fizyolojik rollerinin aydınlatılmasına yardımcı olabilir ve potansiyel biyoteknolojik uygulamalardaki kullanımını yönlendirebilir.

Anahtar Kelimeler

• Enzim inhibisyonu
• eozin
• glutatyon transferaz tau
• Populus trichocarpa

INHIBITION OF GLUTATHIONE TRANSFERASE TAU45 BY EOSIN

Öz

Objective: Glutathione transferases (GSTs) are multifunctional enzymes that catalyze the conjugation of glutathione (GSH) to electrophilic compounds, facilitating detoxication in living systems. In poplar trees, the tau class (GSTU) represents the largest group of GSTs, comprising 81 members. Despite their abundance, the physiological roles and inhibitors for these plant GSTs remain largely unexplored. This study investigates the inhibitory effect of eosin on Populus trichocarpa GSTU45. GST inhibitors may be applied in agricultural biotechnology to overcome herbicide resistance in weeds, and enhance the efficacy of crop protection strategies.

Material and Method: Poplar GSTU45 enzyme was heterologously expressed in Escherichia coli and purified using nickel sepharose affinity chromatography. The inhibitory effect of eosin on enzyme activity was performed spectrophotometrically with 1-chloro-2,4-dinitrobenzene (CDNB).

Result and Discussion: Eosin exhibited moderate inhibition of GSTU45, with an IC₅₀ value of 11.0 ± 1.0 µM against the conventional substrate CDNB. Inhibition kinetics revealed mixed-type inhibition with respect to GSH (K_i = 3.3 ± 0.4 µM) and competitive inhibition with respect to CDNB (K_i = 1.9 ± 0.1 µM), suggesting binding interactions at both the G- and H-sites. These findings provide new insights into the inhibition of tau GSTs and may aid in elucidating their physiological roles and guide their use in potential biotechnological applications.

Anahtar Kelimeler

• Enzyme inhibition
• eosin
• glutathione transferase tau
• Populus trichocarpa

Etik Beyan

The authors declare that the ethics committee approval is not required for this study.

Kaynakça

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