UDP glucose
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| Surname | UDP glucose | |||||||||||||||||||||
| Molecular formula | C 15 H 24 N 2 O 17 P 2 | |||||||||||||||||||||
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| Molar mass | 566.30 g mol −1 | |||||||||||||||||||||
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | ||||||||||||||||||||||
UDP-glucose ( uridine diphosphate - glucose ) is a nucleotide sugar that does not taste sweet. UDP-glucose is used in sugar metabolism as an activated form of glucose as a substrate for glycosyltransferases .
UDP-glucose is a product of a phosphoric anhydride exchange reaction between glucose-1-phosphate (G1P) and uridine triphosphate (UTP).
education
The formation of UDP-glucose is catalyzed by the enzyme UDP-glucose phosphorylase . The phosphate group of the G1P attacks the α-phosphate group of the UTP molecule nucleophilically, releasing pyrophosphate . This is then hydrolytically broken down by pyrophosphatase (inorganic phosphatase) into two phosphate molecules. Due to the hydrolysis of the pyrophosphate, the overall reaction is exergonic:
G1P + UTP → UDP-Glc + PP i (ΔG ° '= 0 kJ / mol)
PP i + H 2 O → 2 P i (ΔG ° '= −33.5 kJ / mol)
→ G1P + UTP + H 2 O → UDP-Glc + 2 P i (ΔG ° '= −33.5 kJ / mol)
Importance in metabolism
UDP-glucose is the building block of glycogen synthesis and thus plays an important role in glucose metabolism. With the release of UDP, a glucose molecule is attached to a glycogen strand. This reaction is catalyzed by glycogen synthase (ΔG ° '= −13.4 kJ / mol). For the overall reaction to lengthen the glycogen strand by one glucose molecule (glycogen (n residues) + G1P + UTP → glycogen (n + 1 residues) + UDP + 2 P i ), a total of one molecule of UTP is required. The resulting UDP is converted back to UTP by reaction with ATP (catalyzed by the nucleoside diphosphate kinase ).
See also
Individual evidence
- ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
- ^ TW Rademacher, RB Parekh, RA Dwek: Glycobiology . In: Annual Review of Biochemistry . tape 57 , no. 1 , June 1, 1988, pp. 785-838 , doi : 10.1146 / annurev.bi.57.070188.004033 .
- ^ D. Voet, JG Voet, CW Pratt: Textbook of Biochemistry , Wiley-VCH 2002.