Analysis of sucrose accumulation in the sugar cane culm on the basis of in vitro kinetic data

Simple item page
dc.contributor.authorRohwer J.M.
dc.contributor.authorBotha F.C.
dc.date.accessioned2011-05-15T16:03:23Z
dc.date.available2011-05-15T16:03:23Z
dc.date.issued2001
dc.description.abstractSucrose accumulation in developing sugar cane (Saccharum officinarum) is accompanied by a continuous synthesis and cleavage of sucrose in the storage tissues. Despite numerous studies, the factors affecting sucrose accumulation are still poorly understood, and no consistent pattern has emerged which pinpoints certain enzyme activities as important controlling steps. Here, we develop an approach based on pathway analysis and kinetic modelling to assess the biochemical control of sucrose accumulation and futile cycling in sugar cane. By using the concept of elementary flux modes, all possible routes of futile cycling of sucrose were enumerated in the metabolic system. The available kinetic data for the pathway enzymes were then collected and assembled in a kinetic model of sucrose accumulation in sugar cane culm tissue. Although no data were fitted, the model agreed well with independent experimental results: in no case was the difference between calculated and measured fluxes and concentrations greater than 2-fold. The model thus validated was then used to assess different enhancement strategies for increasing sucrose accumulation. First, the control coefficient of each enzyme in the system on futile cycling of sucrose was calculated. Secondly, the activities of those enzymes with the numerically largest control coefficients were varied over a 5-fold range to determine the effect on the degree of futile cycling, the conversion efficiency from hexoses into sucrose, and the net sucrose accumulation rate. In view of the modelling results, overexpression of the fructose or glucose transporter or the vacuolar sucrose import protein, as well as reduction of cytosolic neutral invertase levels, appear to be the most promising targets for genetic manipulation. This offers a more directed improvement strategy than cumbersome gene-by-gene manipulation. The kinetic model can be viewed and interrogated on the World Wide Web at http://jjj.biochem.sun.ac.za.
dc.description.versionArticle
dc.identifier.citationBiochemical Journal
dc.identifier.citation358
dc.identifier.citation2
dc.identifier.issn2646021
dc.identifier.other10.1042/0264-6021:3580437
dc.identifier.urihttp://hdl.handle.net/10019.1/12600
dc.subjectConcentration (process)
dc.subjectEnzymes
dc.subjectGenetic algorithms
dc.subjectSugar (sucrose)
dc.subjectTissue
dc.subjectWorld Wide Web
dc.subjectPathway analysis
dc.subjectBiochemistry
dc.subjectglucose transporter
dc.subjectsucrose
dc.subjectarticle
dc.subjectcalculation
dc.subjectcarbohydrate metabolism
dc.subjectcarbohydrate synthesis
dc.subjectcarbohydrate transport
dc.subjectenzyme activity
dc.subjectnonhuman
dc.subjectphytochemistry
dc.subjectplant
dc.subjectpriority journal
dc.subjecttransport kinetics
dc.subjectvalidation process
dc.subjectAgriculture
dc.subjectKinetics
dc.subjectModels, Chemical
dc.subjectPlants
dc.subjectSubstrate Cycling
dc.subjectSucrose
dc.titleAnalysis of sucrose accumulation in the sugar cane culm on the basis of in vitro kinetic data
dc.typeArticle
Files
Collections
Stellenbosch University - Scopus Publications