St Andrews Research Repository

St Andrews University Home
View Item 
  •   St Andrews Research Repository
  • Biology (School of)
  • Biology
  • Biology Theses
  • View Item
  •   St Andrews Research Repository
  • Biology (School of)
  • Biology
  • Biology Theses
  • View Item
  •   St Andrews Research Repository
  • Biology (School of)
  • Biology
  • Biology Theses
  • View Item
  • Login
JavaScript is disabled for your browser. Some features of this site may not work without it.

Influence of cysteine residues on monoamine oxidases catalysis

Thumbnail
View/Open
AnaVintemPhDthesis2003_original_C.pdf (22.55Mb)
Date
2003
Author
Vintém, Ana Paula Barradas
Supervisor
Ramsay, Rona R.
Metadata
Show full item record
Altmetrics Handle Statistics
Abstract
Monoamine oxidases (MAO), types A and B, are flavin-containing enzymes important in the regulation of biogenic amines, including the neurotransmitters, serotonin and dopamine. Cysteine modification inactivates MAO and alters the flavin redox properties, yet the crystal structure has shown that there are no conserved cysteines in the active site of MAO B and that the cysteine 365, modified after inactivation by a cyclopropylamine, was on the surface. The aim of this project was to find how the cysteine residues influence MAO catalysis. MAO A and B cysteine mutants to alanine were constructed and expressed in P. pastoris. MAO A C374A was purified and characterised kinetically. The mutant was active but had decreased Kcₐₜ/kₘ values with a series of substrates compared to the native enzyme. The Kᵢ values for inhibitors were not changed. Mechanism-based inactivators, cyclopropylamines, showed the same pattern as the substrates. Spectra studies and free thiol counts established that 1-phenylcyclopropylamine (1-PCPA) forms a flavin adduct whereas 2-phenylcyclopropylamine (2-PCPA) and A-cyclo- α-methylbenzylamine (N-CαMBA) form adducts with a cysteine in both native and mutant MAO A. Thus, the cysteine modified by N-CαMBA in MAO A is not the 374, as it would be expected by correspondence to the MAO B cysteine 365. For the 1-PCPA and N-CαMBA, the partition ratio was decreased by more than 50%. The data suggest the mutation of cysteine 374 decreases the efficiency of MAO A catalytic process without affecting the ligand binding. A revised mechanism for inactivation of MAO by cyclopropylamines is proposed.
Type
Thesis, PhD Doctor of Philosopy
Collections
  • Biology Theses
URI
http://hdl.handle.net/10023/21860

Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.

Advanced Search

Browse

All of RepositoryCommunities & CollectionsBy Issue DateNamesTitlesSubjectsClassificationTypeFunderThis CollectionBy Issue DateNamesTitlesSubjectsClassificationTypeFunder

My Account

Login

Open Access

To find out how you can benefit from open access to research, see our library web pages and Open Access blog. For open access help contact: openaccess@st-andrews.ac.uk.

Accessibility

Read our Accessibility statement.

How to submit research papers

The full text of research papers can be submitted to the repository via Pure, the University's research information system. For help see our guide: How to deposit in Pure.

Electronic thesis deposit

Help with deposit.

Repository help

For repository help contact: Digital-Repository@st-andrews.ac.uk.

Give Feedback

Cookie policy

This site may use cookies. Please see Terms and Conditions.

Usage statistics

COUNTER-compliant statistics on downloads from the repository are available from the IRUS-UK Service. Contact us for information.

© University of St Andrews Library

University of St Andrews is a charity registered in Scotland, No SC013532.

  • Facebook
  • Twitter