Abstract
Pyrophosphate: D-fructose 6-phosphate 1-phosphotransferase was purified to homogeneity from rice seedlings. The enzyme had an apparent molecular weight of 100,000 and consisted of a single protein. The pH optimum for the forward and reverse reactions was 8.1 and 7.9, respectively. Fructose-2, 6-bisphosphate (Fru-2, 6-P2) shifted the pH optimum for both the forward and reverse reactions to slightly acidic. Half-maximum activation of the enzyme for Fru-2, 6-P2 in the forward and reverse reactions was observed at 16 and 520 nM, respectively. The enzyme had normal Michaelis-Menten kinetics in both the presence and absence of Fru-2, 6-P2. Fru-2, 6-P2 stimulated the enzyme activity by increasing Vmax for Fru-6-P and PPi, and by raising the affinity for Fru-6-P, Fru-1, 6-P2, and PPi. At a saturated concentration of Fru-2, 6-P2 Pi strongly inhibited the enzyme in the forward reaction. The Dixon plots with Pi indicated that the inhibition behavior was of the mixed type with respect to both Fru-6-P and PPi with Ki ...
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
