Textbook Question
Both α-keratin and tropocollagen have helical secondary structure. How do these molecules differ in (a) amino acid composition and (b) three-dimensional structure?
Ch.18 Amino Acids and Proteins
McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 9780134015187
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Table of contents
- Ch.1 Matter and Measurements27
- Ch.2 Atoms and the Periodic Table20
- Ch.3 Ionic Compounds8
- Ch.4 Molecular Compounds23
- Ch.5 Classification & Balancing of Chemical Reactions12
- Ch.6 Chemical Reactions: Mole and Mass Relationships28
- Ch.7 Chemical Reactions: Energy, Rate and Equilibrium64
- Ch.8 Gases, Liquids and Solids24
- Ch.9 Solutions52
- Ch.10 Acids and Bases25
- Ch.11 Nuclear Chemistry22
- Ch.12 Introduction to Organic Chemistry: Alkanes57
- Ch.13 Alkenes, Alkynes, and Aromatic Compounds47
- Ch.14 Some Compounds with Oxygen, Sulfur, or a Halogen50
- Ch.15 Aldehydes and Ketones45
- Ch.16 Amines42
- Ch.17 Carboxylic Acids and Their Derivatives57
- Ch.18 Amino Acids and Proteins82
- Ch.19 Enzymes and Vitamins63
- Ch.20 Carbohydrates44
- Ch.21 The Generation of Biochemical Energy65
- Ch.22 Carbohydrate Metabolism45
- Ch.23 Lipids42
- Ch.24 Lipid Metabolism33
- Ch.25 Protein and Amino Acid Metabolism24
- Ch.26 Nucleic Acids and Protein Synthesis45
McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 9780134015187Not the one you use?Change textbook
Chapter 18, Problem 32
Another endoprotease is trypsin. Trypsin hydrolyzes peptide bonds on the carboxyl side of lysine and arginine. If the following peptide sequence is hydrolyzed by trypsin, how many fragments will there be? Use the three-letter amino acid abbreviations to write the fragments out.
Ala-Phe-Lys-Cys-Gly-Asp-Arg-Leu-Leu-Phe-Gly-Ala
Verified step by step guidance1
Identify the specific action of trypsin: Trypsin hydrolyzes peptide bonds on the carboxyl side of lysine (Lys) and arginine (Arg). This means it cleaves the peptide bond immediately after these amino acids in the sequence.
Examine the given peptide sequence: Ala-Phe-Lys-Cys-Gly-Asp-Arg-Leu-Leu-Phe-Gly-Ala. Locate all instances of lysine (Lys) and arginine (Arg) in the sequence.
Mark the cleavage points: After identifying Lys and Arg, mark the peptide bonds immediately following these residues as the cleavage points. In this sequence, Lys is the third residue, and Arg is the seventh residue.
Determine the resulting fragments: Break the peptide sequence at the marked cleavage points. Write out the fragments using the three-letter amino acid abbreviations. Ensure that each fragment ends at the cleavage point and the next fragment starts immediately after.
Count the number of fragments: After breaking the sequence at the cleavage points, count the total number of resulting fragments to determine how many pieces the peptide has been split into.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Endoprotease Function
Endoproteases, like trypsin, are enzymes that cleave peptide bonds within protein chains, specifically targeting certain amino acids. Trypsin is known for hydrolyzing bonds on the carboxyl side of lysine (Lys) and arginine (Arg), which is crucial for understanding how proteins are broken down into smaller fragments during digestion.
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02:16
Logarithmic Functions
Peptide Bond Hydrolysis
Peptide bond hydrolysis is the process by which water is used to break the bonds between amino acids in a peptide chain. This reaction results in the formation of smaller peptide fragments. In the context of the given peptide sequence, identifying where trypsin acts will determine the number of resulting fragments.
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1:24Peptides Example 1
Amino Acid Abbreviations
Amino acids are often represented by three-letter abbreviations, which are standardized for ease of communication in biochemistry. For example, alanine is abbreviated as Ala, phenylalanine as Phe, lysine as Lys, and so on. Understanding these abbreviations is essential for accurately writing out the fragments produced after trypsin hydrolysis.
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3:03Amino Acid Catabolism: Amino Group Example 2
Related Practice
Textbook Question
Draw the structure of the following amino acids, dipeptides, and tripeptides at low pH (pH 1) and high pH (pH 14). At each pH, assume that all functional groups that might do so are ionized.
a. Val
Textbook Question
If the same peptide found in Problem 18.32 is subjected to acid hydrolysis, how many fragments will result? Why?
Ala-Phe-Lys-Cys-Gly-Asp-Arg-Leu-Leu-Phe-Gly-Ala
Textbook Question
For each of the conjugated proteins described, identify to which class of conjugated protein it belongs.
c. Phosphate groups are attached to this protein.
Textbook Question
For each of the conjugated proteins described, identify to which class of conjugated protein it belongs.
b. Ionized zinc is attached to this protein so the protein can function.
Textbook Question
Draw the structure of the following amino acids, dipeptides, and tripeptides at low pH (pH 1) and high pH (pH 14). At each pH, assume that all functional groups that might do so are ionized.
d. Glu-Asp