Enzyme activities of the isoleucine-valine biosynthetic pathway in streptomycin mutants of Escherichia coli
department or school: Medicine, Faculty of
department or school: Biochemistry and Molecular Biology, Department of
data provider: DSpace
degree campus: UBCV
creator: Lau, D.C.C.
issued: 2011-09-01T19:21:50Z
issued: 1966
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: The compound α-acetolactate has been prepared by the chemical method of Krampltz (1948) and by an enzymatic procedure. The products obtained by each method were characterized chromatographically and spectrophotometrically by conversion to their 2,4—dinitrophenylhydrazone derivatives as well as by conversion to acetoin. The Identity of the hydrazone of enzymatically prepared α-acetolactate with hydrazones of the chemical product was established by comparison of R[subscript: F] values, the identical absorption maxima, and by the infrared spectra of these compounds. The α-acetolactate so obtained was used as substrate in a comparison of the activity in streptomycin mutants of the reductoisomerase enzyme which catalyzes the rearrangement and reduction of α-acetolactate to α,β-dihydroxyisovaleric acid. This reaction is the second step in valine biosynthesis. Streptomycin-dependent mutants of Escherichia coli previously has been shown to be derepressed in acetohydroxy acid synthetase, the enzyme which initiates valine biosynthesis. In addition, it had been reported previously that in streptomycin-dependent E. coli K-12, threonine dehydratase, the enzyme which initiates biosynthesis of isoleucine, also is derepressed. In contrast, reductoisomerase, which is common to both the valine and isoleucine pathway, has been found in this work to be normal (i.e., not derepressed) in streptomycin mutants. An additional enzyme of the common pathway, transaminase B, was found to be about 2 to 3 times higher in streptomycin-dependent mutants than in sensitive or resistant strains. The structural genes for both transaminase B and threonine dehydratase of E. coli K-12 have been shown by genetic studies (Ramakrishnan and Adelberg, 1965b) to be coordinately regulated (i.e., on the same operon). The observations made in this study with streptomycin-dependent E. coli K-12 support the observations of these workers. That is, transaminase B of streptomycin-dependent E. coli K-12 is derepressed c…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/37079
note: ENZYME ACTIVITIES OF THE ISOLEUCINE-VALINE BIOSYNTHETIC PATHWAY IN STREPTOMYCIN MUTANTS OF ESCHERICHIA COLI by D.C.C. LAU B. Sc., University of B r i t i s h Columbia, 196*4-. A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of Biochemistry. We accept t h i s thesis as conforming to the required standard for the degree of MASTER OF SCIENCE. The University of B r i t i s h Columbia A p r i l , 1966. In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of ' • British Columbia, I agree that the Library shall make i t freely available for reference and study. I further agree that per- ; mission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by. his representatives. It is understood that; copying or publi-cation of this thesis for financial gain shall: not be allowed without my written permission. ;- *; ,%-v,x-;.-/, •. ' Department of The University of British Columbia,: Vancouver 8, Canada. j " Date $ , : - 1 -ABSTRACT The compound oU-acetolactate has been prepared by the chemical method of Krampltz (19^8) and by an enzymatic procedure. The products obtained by each method were characterized chromatographically and spectrophotometrically by conversion to t h e i r 2 ,4—dinitrophenylhydrazone derivatives as well as by conversion to acetoin. The Identity of the hydrazone of enzymatically prepared OC-acetolactate with hydrazones of the chemical product was established by comparison of Ep values, the i d e n t i c a l absorption maxima, and by the i n f r a r e d spectra of these compounds. The a-acetolactate so obtained was used as substrate i n a comparison of the a c t i v i t y i n streptomycin mutants of the reductoisomerase enzyme which catalyzes the rearrangement and reduction of a-acetolactate to at,^-dihydroxyisovaleric a c i d . This reaction i s the second step i n valine biosynthesi…
has type: Thesis/Dissertation
is shown at: 10.14288/1.0104692
language: eng
degree discipline: Biochemistry and Molecular Biology
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/37079