Prof Rehana Asghar

Mirpur University of Science and Technology (MUST), Pakistan

Title: Enhanced Thermostability and Enzymatic Activity of Cel6A Variants from Thermobifida fusca by Empirical Domain Engineering (Short Title: Domain Engineering of Cel6A)

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Biography

Dr. Rehana Asghar is presently serving as Professor Emeritus of the Mirpur University of Science and Technology (MUST), Mlrpur. She did her M.Sc. in Botany from the University of Balochistan, Quetta in 1982. She not only got l"Class l" Position in M.Sc. Botany but also scored lST Position in the Faculty of Science. She joined the Department of Botany, University of Balochistan as lecturer in 1984. She was awa rded the Quaid-i-Azam merit scholarship for higher studies in the USA. She did her MS and Ph.D. from the University of California, USA in 1988 and 1992, respectively. On returning from the USA, she joined her parent depa1tment at the University of Balochistan. She did her first Post Doctorate from the University of California in 1993 where she worked as Research Associate from the 29"' Jw1e, 1992 to 24'h Marci1, 1993. She was promoted to the position of Assistant Professor in 1994. After serving for 16 years from the 2"0 April, 1984 to 28'" September, 2000) in the Un.iversity of BaJoch istan, she shifted to d1e PMAS Arid Agriculrure Univers i ty, Rawalpindi. She was appointed as Associa te Professor in 2000. She did her second Post-doctorate again from d1e University of California where she worked as Research Associa te from the l"June, 2004 to 31" May, 2005.

Abstract

Cellulases are a set of lignocellulolytic enzymes, capable of producing eco?friendly low?cost renewable bioethanol. However, low stability and hydrolytic activity limit their wide?scale applicability at the industrial scale. In this work, we report the domain engineering of endoglucanase (Cel6A) of Thermobifida fusca to improve their catalytic activity and thermal stability. Later, enzymatic activity and thermostability of the most efficient variant named as Cel6A.CBC was analyzed by molecular dynamics simulations. This variant demonstrated profound activity against soluble and insoluble cellulosic substrates like filter paper, alkali?treated bagasse, regenerated amorphous cellulose (RAC), and bacterial microcrystalline cellulose. The variant Cel6A.CBC showed the highest catalysis of carboxymethyl cellulose (CMC) and other related insoluble substrates at a pH of 6.0 and a temperature of 60 °C. Furthermore, a sound rationale was observed between experimental findings and molecular modeling of Cel6A.CBC which revealed thermostability of Cel6A.CBC at 26.85, 60.85, and 74.85 °C as well as structural flexibility at 126.85 °C. Therefore, a thermostable derivative of Cel6A engineered in the present work has enhanced biological performance and can be a useful construct for the mass production of bioethanol from plant biomass. Keywords: endoglucanase (Cel6A); domain engineering; Thermobifida fusca; molecular dynamics simulations; thermostable enzymes.