Photosynthesis Research

, 87:195

Kinetic Analysis of the Slow Inactivation of Rubisco During Catalysis: Effects of Temperature, O2 and Mg++

Regular paper

DOI: 10.1007/s11120-005-8386-4

Cite this article as:
Kim, . & Portis, A.R. Photosynth Res (2006) 87: 195. doi:10.1007/s11120-005-8386-4

Abstract

The effect of temperature, O2 and Mg++ on the kinetic characteristics of the slow inactivation (fallover) of Rubisco isolated from spinach (Spinacia oleracea L.) was determined. Comparing 25 and 45 °C, the rate of activity decline of Rubisco increased by 20-fold, but the final ratio of steady state to initial activity increased from 0.38 to 0.62, respectively. Low CO2 increased the extent of fallover but only caused a marginal increase in fallover rate in agreement with results reported previously. In contrast, increased O2 during catalysis significantly increased only the fallover rate. Low Mg++ greatly increased the fallover of Rubisco both in rate and extent. Rubisco carbamylation was assayed using a new separation technique and it revealed that a loss of carbamylation largely accounted for the increased fallover observed with low Mg++. In conclusion, Rubisco fallover is facilitated by high temperature, low concentration of CO2 or Mg++, and high O2. The physiological importance of these factors in affecting Rubisco fallover and contributing to photosynthetic inhibition at high temperatures in planta are discussed.

Keywords

carbamylationmagnesium ionoxygenRubisco fallovertemperature

Abbreviations

Fallover

slow inactivation of Rubisco during catalysis

Rubisco

ribulose-1,5-bisphosph ate carboxylase/oxygenase

ribulose-P2

ribulose-1,5-bisphosphate

pentodiulose-P2

glycero-2,3-diulose-1,5-bisphosphate

xylulose-P2

xylulose-1,5-bisphosphate

carboxytetritol-P2

2′-carboxytetritol-1,4-bisph osphate

carboxyarabinitol-P2

2-carboxyarabinitol-1,5-bisphosphate

Copyright information

© Springer 2006

Authors and Affiliations

  1. 1.U.S. Department of AgriculturePhotosynthesis Research Unit, Agricultural Research ServiceUrbanaUSA
  2. 2.Department of Crop SciencesUniversity of IllinoisUrbanaUSA