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Substrate Inhibition of Maize Endosperm Sucrose Synthase by Fructose and Its Interaction with Glucose Inhibition *
| Content Provider | Semantic Scholar |
|---|---|
| Author | Doehlert, Douglas C. |
| Copyright Year | 2007 |
| Abstract | Sucrose synthase (EC 2.4.1.13) was purified to homogeneity from developing maize lZea mays L.) endosperm. Substrate saturation and inhibitor kinetics were examined for the sucrose synthase reaction. The Km-values for fructose and uridine diphosphate glucose (UDPGlc) were estimated to be 7.8 mM and 76 IlM, respectively. Fructose concentrations over 20 mM inhibited sucrose synthase in an uncompetitive manner with respect to UDPGlc. Glucose was also found to be an uncompetitive inhibitor with respect to both fructose and UDPGlc. At inhibitory concentrations of fructose, the apparent K j for glucose increased linearly with increasing fructose concentration. The results suggest an ordered kinetic mechanism for sucrose synthase where UDPGlc binds first and UDP dissociates last. Fructose and glucose both inhibit by binding to the enzyme-UDP complex. Fructose and glucose, which are present in maize endosperm as the products of invertase, could inhibit sucrose synthase, especially in basal regions of the kernel where hexoses may accumulate. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://naldc.nal.usda.gov/naldc/download.xhtml?content=PDF&id=24342 |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Basal (phylogenetics) Endosperm Fructose Hexoses Invertase Kinetics Internet Protocol Nitric Oxide Synthase Sucrose Uridine Diphosphate Glucose |
| Content Type | Text |
| Resource Type | Article |
