Chemical Forums

Specialty Chemistry Forums => Biochemistry and Chemical Biology Forum => Topic started by: Alexei on November 01, 2020, 10:03:29 AM

Title: Catalytic activity
Post by: Alexei on November 01, 2020, 10:03:29 AM

According to the definition, 1 enzyme unit is the amount of the enzyme that catalyzes the conversion of one micromole of substrate per minute under the specified conditions. But I'm having troubles understanding which unit is used to express the amount of enzyme.

Title: Re: Catalytic activity
Post by: Borek on November 01, 2020, 10:50:59 AM

Doesn't matter. Enzyme unit refers to the enzyme activity, not amount.

You can express the amount of enzyme in solution using any concentration unit, but it won't tell you anything about its activity, which is what - most often - matters.

Title: Re: Catalytic activity
Post by: Babcock_Hall on November 04, 2020, 04:20:33 PM

If one assumes that the enzyme is pure and fully active, then the number of units will be proportional to the mass of the enzyme.  The activity, expressed in units of enzyme, is an extensive property.  The specific activity (which I realize that you did not ask about) is an intensive property. Can you provide some context of your question?