Question

What is the meaning of turnover with reference to enzymes?
A. The number of substrate molecules that molecule of an enzyme converts into products per minute
B. The number of substrate molecules that molecule of an enzyme converts into products per day
C. The number of substrate molecules that molecule of an enzyme converts into products per hour
D. The number of substrate molecules that molecule of an enzyme converts into products per second

Answer 1

Catalysis is a phenomenon in which a chemical termed a catalyst is used to change the rate of a reaction. Enzymes are a type of catalyst that helps to speed up and facilitate a variety of important metabolic events in plants and animals. Enzyme catalysis is a type of catalysis in which enzymes function as a catalyst. Enzymes are proteins that have been folded into complicated forms to accommodate smaller molecules. The active site is the location where these substrate molecules will fit.

Complete answer:
Option A: The number of enzymes that are turned over is used to compare the rates of enzyme-catalyzed processes. It's defined as the number of substrate molecules transformed into product molecules in a certain amount of time (minute).
So, option A is incorrect.
Option B: In the context of enzymes, the turnover number refers to the greatest number of substrate molecules converted to product per second.
So, option B is incorrect.
Option C: To compare the rates of enzyme-catalyzed reactions, the number of enzymes that are turned over is used. It's the number of substrate molecules that are converted into product molecules in a certain amount of time (minute).
So, option C is incorrect.
Option D: Enzymes are catalysts that help speed up chemical reactions without being consumed. The highest number of substrate molecules converted to a product per second is referred to as the turnover number in the context of enzymes. As a result, the correct answer is 'The number of substrate molecules converted into products per second by an enzyme molecule.'
Hence option D is correct.

Hence, Option D is the correct answer.

Note:
When an enzyme is saturated with substrate, its turnover number, or kcat, is the maximum number of molecules of substrate transformed to product per active site per unit time. The maximum velocity is used to calculate this value. The highest number of substrate molecules converted to a product per second is referred to as the turnover number in the context of enzymes. Kcat is the one who represents it. All enzymes have a high turnover rate, but catalase has the greatest.