HR: 0800h
AN: B31B-0992    [Abstracts]
TI: The Influence of Surfaces on the Reaction Kinetics of Biomolecules Under Hydrothermal Conditions
AU: * Cox, J S
EM: jcox@asu.edu
AF: Dept. of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287-1604 United States
AU: Seward, T M
EM: tseward@erdw.ethz.ch
AF: Institut f�r Mineralogie und Petrographie (IMP), ETH-Zurich, Zurich, CH-8092 Switzerland
AB: Surface catalysis and other interferences by reactor vessel walls are an accepted fact in many systems related to chemical engineering or food processing, yet there has been little exploration of this aspect in the geochemical literature with regard to experimental studies of hydrothermal organic reactions. There is an increasing body of evidence that many previous observations may have been influenced to varying degrees by the inside surfaces of the reactor vessels in which they were performed. This influence can take many different forms, such as changes in the observed rates or mechanisms of the reaction, the facilitation of one reaction pathway over another, the presence of unanticipated metal complexing of the reactants or products, and the introduction of new compounds and side reactions. The hydrothermal reaction kinetics of amino acids, oligopeptides, carboxylic acids, and smaller molecular weight molecules in general, appear to all be susceptible to the effects of the surfaces in contact with the solution. This may also provide an approach towards reconciling conflicting published data. A general discussion of these issues will be presented, together with several specific examples from our own experimental studies on the hydrothermal reaction kinetics of aspartic acid and alanine. Experimental data were acquired up to 185°C under hydrothermal conditions using a custom-built gold-lined spectrophotometric reaction cell which permits in situ observation, as well as under lower temperature conditions using different apparatus. Results at similar temperatures, but with different surfaces contacting the solution, will be presented for comparison. Our results indicate that the reaction kinetics of amino acid solutions are significantly different depending on the presence or absence of catalytic surfaces in the reactor such as standard metal alloys. These results will also be discussed in the broader context of understanding complex, natural hydrothermal systems.
UR: http://www.organicgeochemistry.org
DE: 0412 Biogeochemical kinetics and reaction modeling (0414, 0793, 1615, 4805, 4912)
DE: 0450 Hydrothermal systems (1034, 3017, 3616, 4832, 8135, 8424)
DE: 0456 Life in extreme environments
DE: 1055 Organic and biogenic geochemistry
DE: 5215 Origin of life
SC: Biogeosciences [B]
MN: Fall Meeting 2005