Chambers, Stephen Alexander (1989) The production, purification and catalytic utility of lignin peroxidase from "sporotrichum pulverulentum". PhD thesis, University of Warwick.

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Abstract

Production, purification and catalytic utility of lignin
peroxidase (LiP) from Sporotrichum pulverulentum.
The study of Lip has been hampered by the difficulty in
producing this enzyme in sufficient quantities. Several
strains of Phanerochaete chrvsosporium and Sporotrichum
Pulverulentum were screened for LiP expression under
different culture conditions to find a method of producing
adequate supplies of the enzyme for the proceeding work in
this thesis. A reliable method of Lip production was
achieved using 750m1 agitated cultures of S. pulverulentum
containing the detergent tween 80.
Lip from S. pulverulentum was purified by HPLC and was found
to consist of up to 14 isozymes which varied in molecular
weight, pH optimum and specific activity for veratryl
alcohol. However, their catalytic spectra were similar. The
isozymes from S. pulverulentum had higher molecular weights
and lower pI values than those published for LiP from
P. chrvsosporium, which suggested that they were not as
closely related as had been assumed.
Lip from S. pulverulentum was able to oxidise a range of
methoxy-substituted benzyl alcohols to their respective
aldehydes. The susceptibility of benzyl alcohol oxidation by
LiP depended upon the amount and position of methoxyl group
substitution. LiP oxidation of these substrates was
dependent upon how electron-rich the molecular π-orbitals of
the substrates were, but steric effects may also have been
important. LiP oxidation of benzyl alcohols under aerobic
conditions led to additional products such as quinones,
ring-cleavage products and chloro-substituted aromatics.
These latter products provided evidence for the existence of
LiP-derived aryl radical cations for a range of benzyl
alcohol substrates, which is consistent with the
peroxidative one-electron oxidation theory of Lip
degradation of lignin.
In addition LiP was shown to catalyse the peroxidative oneelectron
oxidation of phenolics such as p-cresol and
catechol to produce dimers and polymers.
Lyophilised LiP was shown to be catalytically active in
organic solvents such as ether and propyl acetate. An
increase in enzyme stability of up to 30 times of that in
water and a broadening of its catalytic spectrum was
observed.
Lip was also found in C. versicolor demonstrating that LiP
may be a common constituent of ligninolytic white-rot fungi.
In addition, other. extracellular peroxidases were present in
this fungus. These peroxidases were novel compared to the
extracellular peroxidases from P. chrysosporium since at
least one of these could not oxidise veratryl alcohol and
neither of these peroxidases were manganese-dependent.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QR Microbiology
Library of Congress Subject Headings (LCSH):	Ligninase, Sporotrichum
Official Date:	March 1989
Dates:	Date Event March 1989 Submitted
Institution:	University of Warwick
Theses Department:	Department of Biological Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Dalton, Howard
Sponsors:	Science and Engineering Research Council (Great Britain) (SERC)
Extent:	xxi, 302 p.
Language:	eng
URI:	http://wrap.warwick.ac.uk/id/eprint/4195

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