Contributions of Sucrose Synthase and Invertase to the Metabolism of Sucrose in Developing Leaves 1: Estimation by Alternate Substrate Utilization
AUTOR(ES)
Schmalstig, J. Gougler
RESUMO
The relative contributions of invertase and sucrose synthase to initial cleavage of phloem-imported sucrose was calculated for sink leaves of soybean (Glycine max L. Merr cv Wye) and sugar beet (Beta vulgaris L. monohybrid). Invertase from yeast hydrolyzed sucrose 4200 times faster than 1′-deoxy-1′-fluorosucrose (FS) while sucrose cleavage by sucrose synthase from developing soybean leaves proceeded only 3.6 times faster than cleavage of FS. [14C]Sucrose and [14C]FS, used as tracers of sucrose, were transported at identical rates to developing leaves through the phloem. The rate of label incorporation into insoluble products varied with leaf age from 3.4 to 8.0 times faster when [14C]sucrose was supplied than when [14C]FS was supplied. The discrimination in metabolism was related to enzymatic discriminations against FS to calculate the relative contributions of invertase and sucrose synthase to sucrose cleavage. In the youngest soybean leaves measured, 4% of final laminar length (FLL), all cleavage was by sucrose synthase. Invertase contribution to sucrose metabolism was 47% by 7.6% FLL, increased to 54% by 11% FLL, then declined to 42% for the remainder of the import phase. In sugar beet sink leaves at 30% FLL invertase contribution to sucrose metabolism was 58%.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1054269Documentos Relacionados
- Light/Dark Profiles of Sucrose Phosphate Synthase, Sucrose Synthase, and Acid Invertase in Leaves of Sugar Beets
- Sucrose Accumulation in the Sugarcane Stem Is Regulated by the Difference between the Activities of Soluble Acid Invertase and Sucrose Phosphate Synthase.
- Rapid Repression of Maize Invertases by Low Oxygen. Invertase/Sucrose Synthase Balance, Sugar Signaling Potential, and Seedling Survival1
- Sucrose Synthase Activity in Developing Wheat Endosperms Differing in Maximum Weight 1
- Effect of Night Temperature on the Activity of Sucrose Phosphate Synthase, Acid Invertase, and Sucrose Synthase in Source and Sink Tissues of Rosa hybrida cv Golden Times