Enzymatic production of hexoses
Disclosed herein are methods of producing hexoses from saccharides by enzymatic processes. The methods utilize fructose 6-phosphate and at least one enzymatic step to convert it to a hexose.
1. An enzymatic process for preparing fructose from sucrose, the process comprising the steps of:
(i) a step of converting sucrose to glucose 1-phosphate (G1P) using a sucrose phosphorylase;
(ii) a step of converting G1P to glucose 6-phosphate (G6P), wherein the step is catalyzed by a phosphoglucomutase (PGM)
(iii) a step of converting G6P to fructose 6-phosphate (F6P), wherein the step is catalyzed by a phosphoglucoisomerase (PGI)
(iv) a step of converting F6P to fructose catalyzed by a fructose 6-phosphate phosphatase (F6PP), wherein the process is conducted without adenosine triphosphate (ATP) as a source of phosphate.
2. The process of claim 1 , wherein the process steps are conducted under at least one of the following process conditions:
at a temperature ranging from about 37° C. to about 85° C.,
at a pH ranging from about 5.0 to about 9.0, or
for about 0.5 hours to about 48 hours.
3. The process of claim 1 , wherein the process steps are conducted under at least one of the following process conditions:
without nicotinamide adenosine dinucleotide,
at a phosphate concentration from about 0.1 mM to about 150 mM,
where phosphate is recycled, or
where step (iv) involves an energetically favorable chemical reaction.
4. The process of claim 3 , wherein phosphate is recycled, and the phosphate produced by F6PP dephosphorylation of F6P is used in the process step of converting sucrose to G1P.
5. The process of claim 3 , wherein the step of converting F6P to fructose is an energetically favorable, irreversible phosphatase reaction.
6. The process of claim 1 , wherein the process steps are conducted in a single reaction vessel.