Final answer:
Elastase can substitute for chymotrypsin in a protease assay because both break proteins into peptides and are compatible with the conditions of the assay. However, due to their different specificities for amino acid residues, using elastase instead of chymotrypsin could yield different proteolysis results, which affects the definition of protein domains.
Step-by-step explanation:
Reasons Elastase Can Substitute Chymotrypsin and Potential Differences in Proteolysis Outcomes
For part A of the question, elastase is a good substitute for chymotrypsin in a protease assay for several reasons. Firstly, both enzymes function to break proteins into peptides, which is the fundamental requirement for the assay. Secondly, elastase, like chymotrypsin, is a serine protease produced by the pancreas and released into the duodenum, indicating that it operates under similar physiological conditions as chymotrypsin, suggesting compatibility with the assay conditions.
For part B, proteolysis of the same substrate by chymotrypsin or elastase might yield different results because each protease has specificity for different amino acid residues. Chymotrypsin preferentially cleaves at the carboxyl side of aromatic amino acids, whereas elastase targets smaller, neutral amino acids such as glycine and alanine. Therefore, the pattern of peptide fragments generated will differ between the two enzymes, which can influence the determination of protein domains.
Protein catabolism is a complex process involving various enzymes that cut proteins internally at specific sequences. The fingerprinting technique used in the assay relies on these specific cleavage patterns, and substituting one protease for another could change the resulting peptide fragments pattern, which is critical for accurately defining protein domains.