Date Approved

11-28-2022

Embargo Period

11-29-2022

Document Type

Thesis

Degree Name

M.S. Pharmaceutical Science

Department

Pharmaceutical Sciences

College

School of Health Professions

Advisor

Gregory Caputo, Ph.D.

Committee Member 1

Timothy Vaden, Ph.D.

Committee Member 2

Chun Wu, Ph.D.

Committee Member 3

Kandalam Ramanujachary, Ph.D.

Keywords

Ionic liquids, biomolecules, Trametes versicolor, molecular dynamics

Subject(s)

Laccase; Metalloproteins

Disciplines

Medicinal Chemistry and Pharmaceutics

Abstract

Interactions between ionic liquids and biomolecules have been of great interest due to the intrinsic properties of ionic liquids and the flexibility to mix and match cations and anions to create unique ionic liquids. A number of ionic liquid-biomolecule studies have focused on the interactions with proteins, including industrially relevant enzymes. One of these, laccase from Trametes versicolor, is a naturally derived enzyme used in the breakdown of phenolic compounds in a wide variety of industries, especially useful in breakdown of lignocellulosic materials. Here, a combination of experiments and molecular dynamics (MD) simulations were used to investigate the interactions of ionic liquids with laccase. Enzyme kinetics assays indicated that ionic liquids composed of tetramethylguanidine (TMG) and either serine or threonine caused significant reduction of enzymatic activity, while kinetics was not impacted by TMG-Asp or TMG-Glu ionic liquids. Similarly, intrinsic fluorescence of laccase in the presence of TMG-Ser and TMG-Thr exhibited a shift in spectral properties consistent with structural destabilization, but again TMG-Asp and TMG-Glu had no impact. MD simulations of laccase and ABTS with/without TMG-Ser ionic liquid provide insight into the deactivation mechanism of laccase. The simulations indicate that TMG-Ser disrupts the electron transfer mechanism in laccase.

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