Irreversible thermal inactivation and conformational lock of alpha glucosidase.

Loghman Alaei, Zhila Izadi, Samira Jafari, Fatemeh Jahanshahi, Mehdi Jaymand, Pantea Mohammadi, Bilal Ahamad Paray, Anwarul Hasan, Mojtaba Falahati, Behrang Shiri Varnamkhasti, Ali Akbar Saboury, Zahra Moosavi-Nejad, Mehrnaz Sheikh-Hosseini, Hossein Derakhshankhah

Journal: Journal of biomolecular structure & dynamics 2021;39(9):3256-3262

PMID: 32345145

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Abstract

In the present work, we studied the structure-activity relationship and kinetics of thermal inactivation of α-glucosidase A (AglA) in a 50 mM potassium phosphate buffer at pH 6.8 using -nitrophenyl α-d-glucopyranoside (NPG) as the synthetic substrate following absorbance at 410 nm by UV-Vis spectrophotometer. The interface structure and residual activity plot were analyzed via biochemical measurements by means of conformational lock theory, as well. The thermal inactivation curves were plotted in temperature interval from 30 to 50 °C. Based on experimental and structural data we suggested intermediates during inactivation before the loss of enzyme activity. Arrhenius plot for thermal inactivation rate constant showed biphasic appearance related to before and after 45°C temperature. The contact areas between two subunits were ruptured and unlocked stepwise during dimer dissociation. Cleavage of these areas induced the dissociation of the subunits along with destruction of the active centers and subsequently the loss of activity. It seems that the contact areas interact with active centers by conformational changes involving secondary structural elements.

Address: Pharmaceutical Sciences Research Center, Health Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran.; Department of Biology and Biotechnology, Faculty of Sciences, University of Kurdistan, Sanandaj, Iran.; Pharmaceutical Sciences Research Center, Health Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran.; Zistmavad Pharmed Co, Tehran, Iran.; Student research committee, Faculty of Medicine, Iran University of Medical Science, Tehran, Iran.; Nano Drug Delivery Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran.; Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran.; Department of Zoology, College of Science, King Saud University, Riyadh, Saudi Arabia.; Department of Mechanical and Industrial Engineering, College of Engineering, Qatar University, Doha, Qatar.; Biomedical Research Center, Qatar University, Doha, Qatar.; Department of Nanotechnology, Faculty of Advanced Sciences and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran.; Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.; Department of Biotechnology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran.

DOI: 10.1080/07391102.2020.1762742

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MeSH Terms: Enzyme Stability, Hydrogen-Ion Concentration, Kinetics, Protein Conformation, Temperature, alpha-Glucosidases