Converting enzyme activity to its amount

[kszero]

Im working on a project in which I want to compare fermentation rate of Saccharomyces cerevisiae under different carbohydrates (glucose, sucrose and starch). Glucose and Sucrose aren't causing me any trouble, but when it comes to a starch, its making things complicated. So in order to produce ethanol, starch has to be broken down into maltose or glucose by alpha-amylase and glucoamylase, that can be added seperately to the yeast+starch solution, or be produced by recombinant S. cerevisae.

There are some articles about modified yeast which produces both glucoamylase and alpha-amylase to break down starch. In my study I want to recreate the same "conditions" as they were on those articles. I want add that amount of enzyme which will break down starch, releasing the same amount of glucose as there were on one of the article (dont matter which one). The problem is, that those studies only shows enzyme activity (U/ml), not actual secreted amount of alpha and glucoamylase by yeast. Enzyme activity is expressed as U/ml with one unit defined as the amount of enzyme required to release 1 μmole of glucose per minute. Is there any way to convert U/ml to an actual amount of an enzyme which i can add to my unmodified yeast with starch solution , that it'll produce approximately the same amonut of ethanol as the modified yeast in the articles? Of course i'll keep the same pH and temperature as there were on the studies.

(Sorry for my English, Im still learning it)

 

Articles:

https://biotechnologyforbiofuels.biomedcentral.com/track/pdf/10.1186/1754-6834-6-167.pdf

https://scienceon.kisti.re.kr/commons/util/originalView.do?cn=JAKO200111920885837&oCn=JAKO200111920885837&dbt=JAKO&journal=NJOU00023075

https://academic.oup.com/femsyr/article/18/7/foy085/5061630

 

[BabcockHall]

You might be able to do it using what is called the specific activity of the enzyme.  Specific activity is given as units per milligram of protein.  The denominator is a mass, not a concentration.