University of Illinois Urbana-Champaign

Thermodynamic and kinetic regulation of coupling factor

Grandoni, Patricia Ann

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Description

Title
Thermodynamic and kinetic regulation of coupling factor
Author(s)
Grandoni, Patricia Ann
Issue Date
1989
Doctoral Committee Chair(s)
Ort, Donald R.
Department of Study
Biology
Discipline
Biology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Plant Physiology
Language
eng
Abstract
  • The first part of this thesis focuses on measuring the energetic requirement for activating CF$\sb1$ in DTT-reduced and oxidized thylakoid membranes isolated from spinach, Spinacia oleracea L. The coupling factor complex H$\sp+$-ATPase has latent activity, i.e. it needs to be activated prior to being able to function catalytically. One aspect of activation is the presence of an electrochemical potential, where the magnitude of this potential is assessed as an energetic requirement for CF$\sb1$ activation. For this thesis the energetic requirement was assessed by monitoring the number of single-turnover flashes needed to initiate flash-induced ADP phosphorylation at varying $\Delta$G$\sb{\rm ATP}$ values.
  • The second part of this thesis focuses on investigating the decline in flash yield (the amount of ATP synthesized/flash), seen with both DTT-reduced and oxidized thylakoid membranes, when flash-induced ATP synthesis is measured at elevated $\Delta$G$\sb{\rm ATP}$ values. The data from these experiments show that coupling factor reversibility is not responsible for the drop in flash yield. The presence of the electrochemical potential promotes net ATP synthesis and likewise limits the amount of ATP hydrolysis. The regulatory effect of the electrochemical potential is demonstrated when a partial relaxation of the electrochemical potential enhances hydrolysis. These data suggest that a minimal electrochemical potential is required to activate the complex and this potential must be maintained to maintain the coupling factor in an activated conformation. (Abstract shortened with permission of author.)
Type of Resource
text
Permalink
http://hdl.handle.net/2142/22299
Copyright and License Information
Copyright 1989 Grandoni, Patricia Ann

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