The terminal electron transfer chain of methylophilus methylotrophus
The terminal electron transfer chain of methylophilus methylotrophus
This thesis investigates the terminal electron transport chain of the obligate methylotrophic bacterium Methylophilus methylotrophus during growth on methanol under conditions of oxygen limitation. Under these conditions the sole oxidase in this bacterium is an o-type oxidase which has been solubilized and purified previously by two groups of workers (Carver and Jones, 1983; Froud and Anthony, 1984a) who reported conflicting results. This thesis confirms the work of one of these groups (Froud and Anthony, 1984a). The purified oxidase was found to consist of equal amounts of b-type and c-type cytochromes which correspond to the two types of subunit observed on SDS-PAGE; these had molecular weights of 33,000 and 25,000, respectively. It has been shown that the cytochrome c subunit of the oxidase is completely distinct from cytochrome cL, the electron acceptor for methanol dehydrogenase. This work involved limited proteolysis of the two cytochromes c followed by analysis of the peptides by SDS-PAGE. This conclusion was confirmed byimmunological cross reactivity studies using antiserum raised to the soluble cytochrome cL. It is concluded that the most appropriate name for the o-type oxidase is cytochrome co and not cytochrome cLo as stated in previous work. A method has been developed for incorporating cytochrome co into phospholipid vesicles. The location of the oxidase in a phospholipid membrane did not significantly alter its activity with respect to the oxidation of ascorbate/TMPD, cytochrome cL or cytochrome cH, neither did it result in an increased rate of methanol oxidation by the reconstituted `methanol oxidase system'. It is concluded that the reason for the low rates of methanol oxidation demonstrated by the reconstituted electron transport chain is some factor(s) other than the absence of a phospholipid membrane.
University of Southampton
1988
Ashworth, Helen Mary
(1988)
The terminal electron transfer chain of methylophilus methylotrophus.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
This thesis investigates the terminal electron transport chain of the obligate methylotrophic bacterium Methylophilus methylotrophus during growth on methanol under conditions of oxygen limitation. Under these conditions the sole oxidase in this bacterium is an o-type oxidase which has been solubilized and purified previously by two groups of workers (Carver and Jones, 1983; Froud and Anthony, 1984a) who reported conflicting results. This thesis confirms the work of one of these groups (Froud and Anthony, 1984a). The purified oxidase was found to consist of equal amounts of b-type and c-type cytochromes which correspond to the two types of subunit observed on SDS-PAGE; these had molecular weights of 33,000 and 25,000, respectively. It has been shown that the cytochrome c subunit of the oxidase is completely distinct from cytochrome cL, the electron acceptor for methanol dehydrogenase. This work involved limited proteolysis of the two cytochromes c followed by analysis of the peptides by SDS-PAGE. This conclusion was confirmed byimmunological cross reactivity studies using antiserum raised to the soluble cytochrome cL. It is concluded that the most appropriate name for the o-type oxidase is cytochrome co and not cytochrome cLo as stated in previous work. A method has been developed for incorporating cytochrome co into phospholipid vesicles. The location of the oxidase in a phospholipid membrane did not significantly alter its activity with respect to the oxidation of ascorbate/TMPD, cytochrome cL or cytochrome cH, neither did it result in an increased rate of methanol oxidation by the reconstituted `methanol oxidase system'. It is concluded that the reason for the low rates of methanol oxidation demonstrated by the reconstituted electron transport chain is some factor(s) other than the absence of a phospholipid membrane.
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Published date: 1988
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Local EPrints ID: 461152
URI: http://eprints.soton.ac.uk/id/eprint/461152
PURE UUID: 2c4a7848-4970-4d59-ae01-3768fe9e5575
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Date deposited: 04 Jul 2022 18:36
Last modified: 04 Jul 2022 18:36
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Author:
Helen Mary Ashworth
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