When 4-nitrophenylacetate is used as a substrate for carbonic anhydrase 2 enzyme, is there carbon dioxide as a substrate at the same time?
thank you
Carbonic anhydrase is an enzyme that catalyzes the interconversion between carbon dioxide and water into bicarbonate and protons (or vice versa):
CO2 + H2O HCO3- + H+
However, when 4-nitrophenyl acetate (NPA) is used as a substrate in enzyme assays for carbonic anhydrase, it does not directly involve carbon dioxide. The hydrolysis of NPA by carbonic anhydrase yields 4-nitrophenol and acetate:
NPA + H2O -> 4-nitrophenol + acetate
The rate of this reaction can be monitored spectrophotometrically at 348 nm, providing a convenient assay for carbonic anhydrase activity.
This reaction is used as an alternative assay to measure the enzymatic activity of carbonic anhydrase, especially when it is not feasible to directly measure the conversion of CO2 to bicarbonate. The reason NPA is used is that the reaction it undergoes with carbonic anhydrase is much simpler to measure.
So to answer your question, when 4-nitrophenylacetate is used as a substrate for carbonic anhydrase, there isn't carbon dioxide used as a substrate at the same time. The NPA assay is a separate and alternative way to measure carbonic anhydrase activity.
Nigel Gale thanks for comperhensive response.It was very helpful.
Can you introduce me a reference?
Carbonic anhydrase 2 (CA2) is not typically associated with the hydrolysis of 4-nitrophenyl acetate. CA2 primarily catalyzes the conversion of carbon dioxide to bicarbonate ions and protons. However, there are other classes of enzymes, such as esterases or lipases, that may be involved in the hydrolysis of 4-nitrophenyl acetate. These enzymes cleave the ester bond in 4-nitrophenyl acetate, releasing 4-nitrophenol and acetic acid. If you are specifically referring to the substrate for CA2, it would be carbon dioxide rather than 4-nitrophenyl acetate.
(Also, The substrate for carbonic anhydrase 2 (CA2) is carbon dioxide (CO2). CA2 is an enzyme that catalyzes the reversible conversion of carbon dioxide and water into carbonic acid (H2CO3), which then dissociates into bicarbonate ions (HCO3-) and protons (H+). This enzyme plays a crucial role in maintaining acid-base balance in various tissues and organs of the body.)
Dear Supriya .. thanks for comperhensive response.It was very helpful.