Wine Chemistry and Biochemistry

1 Biochemistry of Alcoholic Fermentation 7

D

Hexose

transporter

D-Glucose

D- Fructose

Glucose-6-phosphate

Hexokinase

Fructose -6-phosphate

ATP

ADP +Pi

Phosphoglucose isomerase

Phosphofructokinase

ATP

ADP +Pi

P l a s m a M e m b r a n e

Cytoplasme

Fructose - 1,6-diphosphate

Dihydoxyacetone

Phosphate Glyceraldehyde -3-phosphate

Aldolase

Triose phosphate

isomerase

Glyceraldehyde

3-phosphate

dehydrogenase

NAD+

NADH + H+

ATP

1,3-diphosphoglycerate

Phosphoglycerate ADP + Pi

kinase

3-phosphoglycerate

Phosphoglycero mutase

Phosphoenol 2-phosphoglycerate

pyruvate

Pyruvate

ATP

ADP

+ Pi

Pyruvate

kinase

Enolase

H 20

Pi

(96 %) (4 %)

D-Glucose

• Fructose

Hexose

transporter

Hexose

transporter

D-Glucose

D-Fructose

Glucose-6-phosphate

Hexokinase

Fructose-6-phosphate

ATP

ADP+Pi

ADP+Pi

Phosphoglucose isomerase

Phosphofructokinase

Grape juice

ATP

P l a s m a M e m b r a n e

Cytoplasme

Fructose-1,6-diphosphate

Dihydoxyacetone

Phosphate

Glyceraldehyd-3-phosphatee

Aldolase

Triose phosphate

isomerase

Glyceraldehyde

3-phosphate

dehydrogenase

NAD+

NADH + H+

ATP

1,3-diphosphoglycerate

Phosphoglycerate ADP + Pi

kinase

3-phosphoglycerate

Phosphoglycero mutase

Phosphoenol 2-phosphoglycerate

pyruvate

Pyruvate

ATP

ADP

+ Pi

Pyruvate

kinase

Enolase

H 20

Pi

(96 %) (4 %)

n

Fig. 1.2Biochemical mechanism of glycolysis

place forming an energy rich bond between the oxidized carbon group and inorganic

phosphate.

The next stage in glycolysis consists of transforming 1,3-diphosphoglycerate into

3-phosphoglycerate. This reaction, which is catalyzed by phosphoglycerate kinase,

releases all the energy contained in the previously formed energy-rich bond, which

the cell uses to phosphorylate one molecule of ADP into ATP.

After this, phosphoglycero mutase converts 3-phosphoglycerate into 2-phospho-

glycerate, which is then dehydrated in phosphoenol pyruvate by the enzyme eno-

lase. Phosphoenol pyruvate contains an energy-rich bond that is used by the enzyme

pyruvate kinase to phosphorylate ADP into ATP. This reaction generates pyruvate,

which is the final product of glycolysis.

As a consequence of glycolysis, each molecule of hexose generates two molecules

of pyruvate, four of ATP and one of NADH. Since two molecules of ATP were