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Towards More Specific Microcalorimetric Studies With Special Emphasis on Biological Systems

Johansson, Peter LU (1998)
Abstract
A new approach in isothermal heat conduction microcalorimetric studies of chemical and biological processes is explored. The general (non-specific) method of calorimetry is combined with more specific analytical methods of analysis to "multi-functional microcalorimetric process monitors".



A microcalorimeter with specific analytical sensors placed in the reaction vessel for studies of processes in solutions is described. The vessel incorporates pH/pO2 electrodes and a fibre optic spectrophotometer for absorbance measurements. Dynamic properties of the calorimeter was investigated in electrical calibration experiments. The instrument was tested with different systems: (a) Titration measurements with a weak base. The... (More)
A new approach in isothermal heat conduction microcalorimetric studies of chemical and biological processes is explored. The general (non-specific) method of calorimetry is combined with more specific analytical methods of analysis to "multi-functional microcalorimetric process monitors".



A microcalorimeter with specific analytical sensors placed in the reaction vessel for studies of processes in solutions is described. The vessel incorporates pH/pO2 electrodes and a fibre optic spectrophotometer for absorbance measurements. Dynamic properties of the calorimeter was investigated in electrical calibration experiments. The instrument was tested with different systems: (a) Titration measurements with a weak base. The experiment as a model for titrations in ligand-binding studies is discussed. (b) The performance of the system in biological experiments is tested with growth of bacteria. Studies of growing cells where the dependence of the calorimetric signal on pH, oxygen concentration and turbidity is studied. Exemplified with E.coli in a complex medium under oxygen-limiting conditions. (c) Thermodynamic and kinetic studies of the hydrolysis of acetyl salicylic acid in basic buffer. Pseudo first order rate constants calculated from calorimetric and absorbance data are compared. (d) Studies of the oxidation of L-ascorbic acid with consecutive hydrolysis of the oxidation product. Overlapping reactions are deconvoluted and characterised kinetically and thermodynamically.



A microcalorimetric gas perfusion system with a calorimetric CO2 analyser connected on-line is described. The instrument is mainly intended for studies of plant energetics and general metabolism in the dark. The system was tested in metabolic experiments of freshly cut potato tuber slices (Solanum tuberosum).



The perfusion system was further developed to incorporate light-guides for the study of radiant energy uptake by photobiological / photochemical processes. A green leaf (Spinacia oleracea) was used as a test sample for the instruments. The conservation of light energy and CO2 in the tissue is measured and the energy / CO2 budget discussed. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • prof Lamprecht, Ingolf
organization
publishing date
type
Thesis
publication status
published
subject
keywords
isothermal heat conduction micro calorimetry spectrophotometry diode array pH oxygen titration chemical reaction biological bacteria perfusion photo carbon dioxide plant enthalpy Gibbs energy kinetic, Biology, Biologi
pages
140 pages
publisher
The secretary at the Division of Thermochemistry, Lund University, Box 124, 221 00 Lund,
defense location
Lecture hall G, Center for Chemistry and Chemical Engineering
defense date
1998-05-22 10:15
external identifiers
  • Other:LUNKDL/(NKTK-14)/140/(1998)
language
English
LU publication?
yes
id
1390f647-ef25-43a5-8359-b7d3eeb2795f (old id 38773)
date added to LUP
2007-08-01 10:41:24
date last changed
2016-09-19 08:45:14
@misc{1390f647-ef25-43a5-8359-b7d3eeb2795f,
  abstract     = {A new approach in isothermal heat conduction microcalorimetric studies of chemical and biological processes is explored. The general (non-specific) method of calorimetry is combined with more specific analytical methods of analysis to "multi-functional microcalorimetric process monitors".<br/><br>
<br/><br>
A microcalorimeter with specific analytical sensors placed in the reaction vessel for studies of processes in solutions is described. The vessel incorporates pH/pO2 electrodes and a fibre optic spectrophotometer for absorbance measurements. Dynamic properties of the calorimeter was investigated in electrical calibration experiments. The instrument was tested with different systems: (a) Titration measurements with a weak base. The experiment as a model for titrations in ligand-binding studies is discussed. (b) The performance of the system in biological experiments is tested with growth of bacteria. Studies of growing cells where the dependence of the calorimetric signal on pH, oxygen concentration and turbidity is studied. Exemplified with E.coli in a complex medium under oxygen-limiting conditions. (c) Thermodynamic and kinetic studies of the hydrolysis of acetyl salicylic acid in basic buffer. Pseudo first order rate constants calculated from calorimetric and absorbance data are compared. (d) Studies of the oxidation of L-ascorbic acid with consecutive hydrolysis of the oxidation product. Overlapping reactions are deconvoluted and characterised kinetically and thermodynamically.<br/><br>
<br/><br>
A microcalorimetric gas perfusion system with a calorimetric CO2 analyser connected on-line is described. The instrument is mainly intended for studies of plant energetics and general metabolism in the dark. The system was tested in metabolic experiments of freshly cut potato tuber slices (Solanum tuberosum).<br/><br>
<br/><br>
The perfusion system was further developed to incorporate light-guides for the study of radiant energy uptake by photobiological / photochemical processes. A green leaf (Spinacia oleracea) was used as a test sample for the instruments. The conservation of light energy and CO2 in the tissue is measured and the energy / CO2 budget discussed.},
  author       = {Johansson, Peter},
  keyword      = {isothermal heat conduction micro calorimetry spectrophotometry diode array pH oxygen titration chemical reaction biological bacteria perfusion photo carbon dioxide plant enthalpy Gibbs energy kinetic,Biology,Biologi},
  language     = {eng},
  pages        = {140},
  publisher    = {ARRAY(0x96f0a60)},
  title        = {Towards More Specific Microcalorimetric Studies With Special Emphasis on Biological Systems},
  year         = {1998},
}