Regulation of fructose-1,6-bisphosphatase activity in leaves

✍ Scribed by Richard C. Leegood; David A. Walker

• Publisher: Springer-Verlag
• Year: 1982
• Tongue: English
• Weight: 791 KB
• Volume: 156
• Category: Article
• ISSN: 0032-0935
• DOI: 10.1007/bf00393316

✦ Synopsis

) activity increased markedly (greater than 10-fold) upon illumination of wheat leaves. Darkening caused a relatively slow but complete reversal of light activation. The effects of 02 and CO 2 concentration and light intensity on fructosebisphosphatase activation were measured. In ratelimiting light, 2% 02 stimulated enzyme activity, whereas varying the CO2 concentration had little effect. In saturating light, lowering the oxygen tension had no effect, but CO2 at near-saturating concentrations for photosynthesis inhibited enzyme activity. Dark inactivation of the enzyme was completely prevented by incubation of leaves in N2, but was facilitated by 02, indicating that 02 is the major oxidant in darkened leaves. It is argued that while fructose bisphosphatase is redox-regulated in leaves, modulation of enzyme activity by this mechanism is unlikely to contribute to the regulation of CO2 fixation in leaves.