ROLE OF SUBSTRATE BINDING ON THE PROTEIN DYNAMICS OF AN ENDOGLUCANASE FROM FUSARIUM OXYSPORUM AT DIFFERENT TEMPERATURES

Abstract

: Thermostability is an important requirement for protein function, and one goal of protein engineering is improvement of activity of the enzymes at higher temperatures, particularly for industrial applications. Computational approaches to investigate factors influencing thermostability of proteins are becoming researchers’ choice. This study investigates the influence of substrate binding on the protein dynamics by comparing the molecular dynamics simulations of substrate-enzyme complex against un-bound enzyme, using endoglucanase I from Fusarium oxysporum. Endoglucanase-substrate complex was prepared by docking and molecular dynamics simulations were carried out at three different temperatures, 313 K, 333 K and 353 K. Our finding shows that the secondary structures for substrate-enzyme complex show more fluctuations relative to un-complexed structure. The same trend was observed for solvent accessible surface area and radius of gyration. At the highest temperature studied (353 K), the substrate-enzyme complex form showed the highest fluctuations. The fluctuations around the active site regions reach a minimum at the optimum temperature, compared to the other structural regions and other temperatures. ABSTRAK: Kestabilan (ketahanan) terhadap haba merupakan keperluan yang penting untuk fungsi protin, salah satu matlamat kejuruteraan protin adalah penambahbaikan aktiviti enzim pada suhu yang tinggi khususnya untuk aplikasi industri. Kini para penyelidik memilih kaedah komputasi, bagi mengkaji faktor yang mempengaruhi kestabilan terhadap haba. Kajian ini menyelidik pengaruh ikatan substrat pada protin dengan membandingkan simulasi molekular dinamik diantara substrat-enzim kompleks dan enzim sahaja, menggunakan endoglucanase I dari Fusarium oxysporum. Kompleks endoglucanase-substrat disediakan melalui kaedah docking dan simulasi molekular dinamik dilakukan pada suhu 313 K, 333 K dan 353 K. Kajian kami menunjukkan struktur sekunder bagi substrat-enzim kompleks kurang stabil berbanding enzim sahaja. Pola yang sama bagi luas permukaan boleh dicapai pelarut (SASA) dan jejari gyrasi. Pada suhu tertinggi dikaji (353 K), substrat-enzim kompleks paling tidak stabil. Pada suhu optimum, kadar ubah-ubah sekitar amino asid aktif adalah minimum berbanding struktur dan suhu lain.

Keywords

• thermostable enzymes
• thermostability factors
• ligand-enzyme complex
• fusarium oxysporum endoglucanase
• molecular dynamics simulations