Competitive inhibition of phosphoglucose isomerase of apple leaves by sorbitol 6-phosphate
Apple leaf cytosolic phosphoglucose isomerase (PGI, EC 5.3.1.9) was purified to an apparent homogeneity with a specific activity of 2456 units/mg protein, and chloroplastic PGI was partially purified to a specific activity of 72 units/mg protein to characterize their biochemical properties. These tw...
| Veröffentlicht in: | Journal of plant physiology. - 1979. - 165(2008), 9 vom: 16. Juni, Seite 903-10 |
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| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2008
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| Zugriff auf das übergeordnete Werk: | Journal of plant physiology |
| Schlagworte: | Journal Article Fructosephosphates Hexosephosphates Sugar Phosphates sorbitol 6-phosphate 20479-58-7 Glucose-6-Phosphate 56-73-5 erythrose 4-phosphate 585-18-2 mehr... |
| Zusammenfassung: | Apple leaf cytosolic phosphoglucose isomerase (PGI, EC 5.3.1.9) was purified to an apparent homogeneity with a specific activity of 2456 units/mg protein, and chloroplastic PGI was partially purified to a specific activity of 72 units/mg protein to characterize their biochemical properties. These two isoforms showed differential responses to heat treatment; incubation at 50 degrees C for 10 min resulted in a complete loss of the chloroplastic PGI activity, whereas the cytosolic PGI only lost 50% of its activity. Apple cytosolic PGI is a dimeric enzyme with a molecular mass of 66 kDa for each monomer. The activity of both isoforms was strongly inhibited by erythrose 4-phosphate (E4P) with a K(i) of 1.2 and 3.0 microM for the cytosolic PGI and chloroplastic PGI, respectively. Sorbitol 6-phosphate (Sor6P), an intermediate in sorbitol biosynthesis, was found to be a competitive inhibitor for both cytosolic and chloroplastic PGIs with a K(i) of 61 and 40 microM, respectively. PGIs from both spinach and tomato leaves were also inhibited by Sor6P in a similar manner. The possible physiological significance of this finding is discussed |
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| Beschreibung: | Date Completed 22.04.2009 Date Revised 07.12.2022 published: Print-Electronic Citation Status MEDLINE |
| ISSN: | 1618-1328 |
| DOI: | 10.1016/j.jplph.2007.12.002 |