[aqhl]

Hi, I have a small question. Why in alcoholic fermentation, only sugar 6 is transformed ? Which enzymes can transform sugar 6 ?

[Equi]

Alcoholproduction is just the very last step to regnerate NAD+ levels under anaerobic conditions. Hence, there are many enzymes involved.

[aqhl]

Is there any enzyme that converts sugar 5 to alcohol ?

[Equi]

Not to ethanol in one step, no.

[aqhl]

ok, can you explain me how they are different ?

[Equi]

I don't get it.

It would be extremely helpful if you phrase out your questions properly.

[aqhl]

I have read a little about alcoholic fermentation. some bacteria can change sugar 5 to alcohol. but ferment, only change sugar 6 to alcohol. I dont know why ?

[Equi]

A crucial step in many alcoholic fermentation is the decarboxylation of Pyruvate (C3 -> C2). Pyruvate is the endproduct of glycolysis. I guess that C5 sugars aren't processed in glycolysis and therefore no Pyruvate is produced. No Pyruvate, no acetaldehyde, no ethanol.

Take a look at some basic biochemistry or microbiology textbooks like Lehninger and Brocks respectively. They should have a some more detail on this matter.