Aquatic Sciences Meeting, Albuquerque 2001

PC08 New Techniques and Technologies from Single Cells to the Global Ocean

Date: Wednesday, February 14, 2001

Location: Southwest Hall

Scott, K, M, Harvard University, Cambridge, USA, kscott@oeb.harvard.edu

Robinson, J, J, Harvard University, Cambridge, USA, Jonathan.Robinson@ejgallo.com

Schwedock, J, , Harvard University, Cambridge, USA, julie@genprosys.com

Cavanaugh, C, M, Harvard University, Cambridge, USA, cavanaug@fas.harvard.edu

KINETIC PARAMETERS OF FORM I AND FORM II RUBISCOS FROM CHEMOAUTOTROPHIC SYMBIOSES

RubisCO, which catalyzes CO2 fixation in the Calvin cycle, occurs as catalytically and structurally distinct forms. Form I and Form II RubisCO have been detected in different marine invertebrate-chemoautotroph symbioses. The broad range in stable carbon isotope values of these symbioses, from –9 to –39 per mil, is hypothesized to be affected by the degree to which different forms of RubisCO fractionate CO2 during fixation. Here, the Michaelis constants and maximal velocities of Form I and Form II RubisCOs from hydrothermal vent and coastal chemoautotrophic symbioses are compared, and their kinetic isotope effects are being determined. These parameters will be discussed with respect to the environmental and host internal CO2 concentrations, and growth rates of these associations. Evaluating the degree to which the kinetic isotope effect of RubisCO influences the stable carbon isotope composition in these and in other autotrophs are crucial for the correct interpretation of stable carbon isotope ratios in both contemporary and fossil biomass.

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Aquatic Sciences Meeting, Albuquerque 2001

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