Abstract
Chymotrypsin is a typical digestive enzyme which is mainly used in the digestion of proteins through a process commonly known as proteolysis. The enzyme chymotrypsin often cleaves bonds of peptide amide preferentially where a carboxyl side of that bond is a tryptophan, phenylalanine or tyrosine.
In this experiment, the chymotrypsin molecules were arranged in such a manner that all the enzyme molecules began the catalytic process at the same time. The rate at which the p-nitrophenol was being generated was initially rapid which was then followed by a much slower hydrolysis rate at steady state.
Therefore, the experiment essentially did sort to establish the concentration of the enzymes after several runs, the concentration of the stock enzyme solution and the rates of hydrolysis.
Introduction
Chymotrypsin is an enzyme of the digestive system that is synthesized or produced in the pancreas through a process known as biosynthesis of protein precursor, chymotrypsinogen. Chymotrypsinogen is also an enzyme though it is often in its inactive state. It is usually activated by trypsin through cleavage process. The compound generated after cleavage is active chymotrypsin and it consists of three polypeptide molecules connected by disulfide bonds.
The proteolytic enzyme acts in the mammalian digestive system an also in other higher organisms. It enables cleavage of peptide amide bonds through a process called hydrolysis reaction. The hydrolytic cleavage process would otherwise take place, but it is usually too slow when there is no catalyst. The substrates that are often acted upon by chymotrypsin include tyrosine, leucine, tryptophan, methionine and phenylalanine. These substrates are always cleaved the point of carboxyl bond.
The figure below shows the mechanism of the action of chymotrypsin enzyme.
Chymotrypsin’s active sites consists of a large number of reactive groups that are ever in a more close proximity to the sites where the hydrophobic amines bond. These binding sites are deep pockets that are lined with amino acid chains that are hydrophobic. These amino acids are always involved in the hydrolytic reactions that take place. The figure below further illustrates the action of chymotrypsin.
Materials and Methods
A stock chymotrypsin enzyme of concentration 5.0 mg/mL was availed for used and was at all times kept in an ice bath. Other assay solutions were prepared and then kept at room temperature. The assay solutions prepared were placed in glass cuvets and then covered with paraffin. The cuvet contents were then vigorously mixed. The solution mixture was then tested in an A400 spectrophotometer to zero the solution first. The absorbance was then closely monitored for one minute just to ensure that the absorbance reading would not be altered by any contaminations in the test specimen. There after, 100 µL of NPA solution was added to the cuvet contents and then rapidly mixed. The cuvet and its content were then placed in the spectrophotometer and the reading of absorbance at A400 taken after every thirty seconds for five minutes. The cuvet was then rinsed thoroughly with deionized water in preparation for another run.
