Sedoheptulose-7-phosphate

Structural formula
D -edoheptulose-7-phosphate
General
Surname	Sedoheptulose-7-phosphate
other names	S7P
Molecular formula	C 7 H 15 O 10 P
External identifiers / databases
CAS number 2646-35-7 PubChem 165007 Wikidata Q3040325
properties
Molar mass	290.16 g mol −1
safety instructions
GHS labeling of hazardous substances H and P phrases H: 302-315-319-335 P: 261-305 + 351 + 338
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Sedoheptulose-7-phosphate is an ester of sedoheptulose and phosphoric acid . It is an intermediate in the pentose phosphate route  (PPP). In carbohydrate metabolism plays D isomer a central role.

Reactions

Catalyzed transfer of a dihydroxyacetone group from sedoheptulose-7-phosphate (1) to glyceraldehyde-3-phosphate (2). Therefore, the transaldolase is also called dihydroxyacetone transferase. Erythrose-4-phosphate (3) and fructose-6-phosphate (4) are formed.

D -edoheptulose-7-phosphate is an important intermediate in the non-oxidative (reversible) section of the pentose phosphate pathway .

Under the action of the enzyme transaldolase , it can arise from erythrose-4-phosphate and fructose-6-phosphate , together with glyceraldehyde-3-phosphate . A dihydroxyacetone group is transferred in the reaction . Alternatively, S7P is formed by a transketolase reaction, in which case the transketolase catalyzes the transfer of a C2 unit ( glycolaldehyde group ) from xylulose-5-phosphate to ribose-5-phosphate , so that glyceraldehyde-3-phosphate is formed from the former and sedoheptulose-7- from the latter. phosphate arise.

S7P is also formed by the enzyme sedoheptulokinase ( EC  2.7.1.14 ) from sedoheptulose and ATP , according to:

${\displaystyle \mathrm {{\text{Sedoheptulose}}+ATP\longrightarrow } }$ ${\displaystyle \mathrm {{\text{Sedoheptulose-7-phosphat}}+ADP} }$

This means that S7P can be fed directly into the carbohydrate metabolism, analogously to glucose-6-phosphate by means of glucokinase .

Finally, the enzyme sedoheptulose bisphosphatase (SPBase) ( EC  3.1.3.37 ) catalyzes the hydrolysis of sedoheptulose 1,7-bisphosphate to S7P according to:

${\displaystyle \mathrm {{\text{Sedoheptulose-1,7-bisphosphat}}+H_{2}O\longrightarrow } }$ ${\displaystyle \mathrm {{\text{Sedoheptulose-7-phosphat}}+P_{i}} }$

In plants, the SPBase is used in the Calvin cycle to make S7P available to the non-oxidative pentose phosphate pathway. In yeast, the SPBase produces S7P, which later plays a role in riboneogenesis , the formation of ribose-5-phosphate without the formation of NADPH .

Individual evidence

1. ↑ ^{a b} Data sheet D-sedoheptulose 7-phosphate disodium salt, ~ 95% from Sigma-Aldrich , accessed on September 28, 2014 ( PDF ).
2. ^ H. Robert Horton, Laurence A. Moran, K. Gray Scrimgeour, Marc D. Perry, J. David Rawn and Carsten Biele (translators): Biochemie . Pearson Studies; 4th updated edition 2008; ISBN 978-3-8273-7312-0 ; Pp. 490-496.
3. ↑ Nagy, C. and Haschemi, A. (2013): Sedoheptulose kinase regulates cellular carbohydrate metabolism by sedoheptulose 7-phosphate supply. In: Biochem Soc Trans . 41 (2); 674-680; PMID 23514175 ; doi : 10.1042 / BST20120354
4. ↑ Michelle F. Clasquin et al. (2011): Riboneogenesis in Yeast . In: Cell 145 (6) : 969-980; doi : 10.1016 / j.cell.2011.05.022 , PDF (full text access, English)