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1. (WO2018114575) RÉDUCTION ENZYMATIQUE DE CYSTINE
Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

CLAIMS

1. Method for the enzymatic reduction of cystine to cysteine comprising contacting cystine with a reduction solution comprising:

(i) an active glutathione reductase (EC1.8.1.7);

(ii) a cofactor; and

(iii) glutathione;

and recovering a cysteine comprising composition,

wherein the reduction solution has a pH of at least 6 during contacting with cystine.

2. Method according to claim 1 , wherein the step of recovering the cysteine comprising composition is carried out within 15 hours after the step of contacting cystine with the reduction solution.

3. Method according to claim 1 or claim 2, wherein the cofactor is nicotinamide adenine dinucleotide phosphate (NADPH), preferably in oxidized form (NADP+) or nicotinamide adenine dinucleotide (NADH), preferably in oxidized form (NAD+).

4. Method according to any of claims 1 to 3, wherein the glutathione reductase is comprised in a permeabilized microorganism.

5. Method according to any of the claims 1 to 4, wherein the glutathione reductase is comprised in a cell free extract, preferably wherein the cell free extract is derived from yeast or fungi by enzymatic, mechanical or chemical disruption of yeast or fungi cells followed by separating the soluble fraction from the cells walls to provide the cell free extract.

6. Method according to any of the claims 1 to 5, wherein the reduction solution further comprises:

(iv) a cofactor regeneration system comprising glucose dehydrogenase and glucose or formate dehydrogenase and formate.

7. Method according to any of the claims 1 to 6, wherein the molar ratio of the glutathione: cystine in the reduction solution is less than 0.1.

8. Method according to any of the claims 1 to 7, wherein the reduction solution has a pH within the range of 7.0 to 8.5.

9. Method according to any of the claims 1 to 8, wherein the cystine is contacted with the reduction solution for a time period which is sufficient to reduce more than 50% of the cystine to cysteine.

10. Method according to any of the claims 1 to 9, wherein contacting the cystine with the reduction solution is carried out under anaerobic conditions.

1 1. Method according to any of the claims 1 to 10, wherein the cysteine comprising composition comprises cysteine and one or more selected from gluconic acid, formic acid, glucose, formate, nicotinamide adenine dinucleotide phosphate, nicotinamide adenine dinucleotide, glutathione and glutathione reductase.

12. A composition comprising cysteine and one or more selected from gluconic acid, formic acid, glucose, formate, nicotinamide adenine dinucleotide phosphate, nicotinamide adenine dinucleotide, glutathione, acetone, acetaldehyde and glutathione reductase.

13. Use of a composition as defined in claim 12 as a natural food flavour.

14. A reduction solution comprising:

(i) an active glutathione reductase (EC1.8.1.7);

(ii) a cofactor; and

(iii) glutathione.