Qian Zhou


Threonine dehydrogenase from E.coli is a member of the medium-chain, Zn2+-containing alcohol dehydrogenase family. A site-directed mutant of theronine dehydrogenase was prepared at position 88 by replacing the native glutamate with cysteine using polymerase chain reaction. The mutated enzyme, designated TDH E88C, was expressed and purified to homogeneity in a three-step chromatographic procedure. The activity of the mutant after each step of purification was determined by a specific assay. Both the total activity and the specific activity of TDH E99C were significantly decreased compared to the wild-type TDH. The mutant enzyme was not sufficiently stable to obtain reliable Vmax or Km values, preventing a quantitative comparison to the wild type enzyme. Therefore, a definitive conclusion on the role of the Glu-88 remains unresolved, pending further studies in the future.

Library of Congress Subject Headings

Alcohol dehydrogenase; Escherichia coli; Chemical mutagenesis

Publication Date


Document Type


Department, Program, or Center

School of Chemistry and Materials Science (COS)


Craig, Paul


Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works. Physical copy available through RIT's The Wallace Library at: QP603.A34 Z568 1999


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