The primary structure of β-endorphin, a peptide containing...

The primary structure of $\beta$ -endorphin, a peptide containing 31 amino acids synthesized by the body to control pain, is shown here: Tyr-Gly-Gly-Phe-Met-Thr-Ser-Glu-Lys-Ser-GIn-Thr-Pro-Leu-Val-ThrLeu-Phe-Lys-Asn-Ala-Ile-Ile-Lys-Asn-Ala-Tyr-Lys-Lys-Gly-Glu a. What fragments are obtained as a result of treatment with each of the following? 1. trypsin 2. cyanogen bromide 3. chymotrypsin

The primary structure of $\beta$ -endorphin, a peptide containing 31 amino acids synthesized by the body to control pain, is shown here:
Tyr-Gly-Gly-Phe-Met-Thr-Ser-Glu-Lys-Ser-GIn-Thr-Pro-Leu-Val-ThrLeu-Phe-Lys-Asn-Ala-Ile-Ile-Lys-Asn-Ala-Tyr-Lys-Lys-Gly-Glu
a. What fragments are obtained as a result of treatment with each of the following?
1. trypsin
2. cyanogen bromide
3. chymotrypsin

Key Concepts

Chymotrypsin

Chymotrypsin is a proteolytic enzyme that preferentially cleaves peptide bonds at the carboxyl side of aromatic amino acids such as phenylalanine, tyrosine, and tryptophan. Its action is crucial in studies that require selective cleavage of polypeptides to analyze protein structure and function.

Trypsin

Trypsin is a serine protease that specifically cleaves peptide bonds at the carboxyl side of the amino acids lysine and arginine, except when these residues are immediately followed by proline. Its highly specific activity makes trypsin a valuable tool in protein sequencing and mass spectrometry analysis.

Cyanogen Bromide

Cyanogen bromide is a chemical reagent that cleaves proteins specifically at the carboxyl side of methionine residues. Unlike enzymatic cleavage, its chemical reaction provides a predictable cleavage pattern, which is particularly useful in mapping protein sequences and generating peptide fragments for further analysis.

Proteolytic Enzymes

Proteolytic enzymes are a group of enzymes that break peptide bonds within proteins, fragmenting them into smaller pieces. This cleavage is not random but follows specific patterns based on the enzyme’s recognition sites. They are extensively used in biochemistry for mapping protein structures and for preparative protein digestion.

Primary Protein Structure

The primary protein structure refers to the linear sequence of amino acids that make up a protein. This sequence is critical because it determines all of the protein's subsequent levels of structure and ultimately its function. Understanding the primary structure is fundamental to studying how proteins are processed and modified by various enzymes.

Enzyme Cleavage Specificity

Each proteolytic enzyme or cleavage reagent exhibits specificity for certain amino acid residues or sequences within a protein. For instance, trypsin cleaves after basic residues such as lysine and arginine, chymotrypsin targets aromatic residues, and cyanogen bromide cleaves specifically at the methionine residue. This specificity allows scientists to predict and analyze the pattern of protein fragmentation.

Please give Ace some feedback