1. Some websites state that the enzyme zymase (which I understand to be a complex of several enzymes) is responsible for catalyzing glycolysis in order to produce pyruvate.

  2. On the other hand, some other websites state that zymase is responsible for catalyzing the conversion of pyruvate to acetaldehyde, and acetaldehyde to ethanol and carbon dioxide.

Which one of the above is correct? And, what are the names of the enzymes that are collectively called zymase.

I thank you for your time and consideration. Good day!


This is all correct it seems, but maybe the term is more of historical interest rather than current science.

Zymase is a term which is no longer in use in the scientific literature. It seems to have disappeared in the 1950s. The latest reference I can see is 1970s.

The reason seems to be that Zymase was purifiable from yeast with 19th century techniques. The term was coined in 1897. This is probably because in brewers yeast the Zymase components are either in a protein complex or contained within a compartment in the cell that could be separated from the rest of the organism. Here's an early reference - german isn't so great.

The Zymase activity was shown to vary from one strain of yeast to another, which makes the discovery seem more a manifestation of the physiology of that one strain of yeast.

Later work showed that Zymase activity was organizable into a more universal set of genes which are conserved in all living things and called the 'citric acid cycle' or the Krebs Cycle. Krebs performed his work without reference to Zymase, where biochemicals were added to a culture and their transformation tracked. So, Zymase seems more like a historical footnote...

Wikipedias' entry sounds as if the extraction was not very pure - its called a 'press juice' so I think it would be difficult to describe exactly which specific enzymes were in Zymase. I'd naively assume that nearly all the citric acid cycle enzymes would be involved in Zymase activity, where observed.

Many of the enzymes in the citric acid cycle form large complexes with themselves and other of the enzymes, which might be responsible for the original discovery of Zymase.

  • $\begingroup$ The linked german paper is a reproduction from 1935, so I don't think it is evidence that the term is still used $\endgroup$ Oct 21 '13 at 15:12
  • $\begingroup$ good point - fixed. $\endgroup$
    – shigeta
    Oct 21 '13 at 17:24

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