Y1S2 003 II Biochem Protein Analysis Techniques
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Questions and Answers

What is the primary bond responsible for holding two amino acids together?

  • Peptide bond (correct)
  • Ionic attraction
  • Hydrogen bond
  • Covalent sulfur bond
  • What type of interactions are responsible for the tertiary structure of a protein?

  • Hydrophobic and hydrophilic interactions (correct)
  • Hydrogen bonds and peptide bonds
  • Hydrophobic and ionic interactions
  • Covalent sulfur bonds and ionic attraction
  • What is the term for the process of disrupting the native structure of a protein?

  • Protein catalysis
  • Protein synthesis
  • Protein denaturation (correct)
  • Protein folding
  • What is the role of enzymes in biological reactions?

    <p>To increase the rate of reaction by lowering the energy of activation</p> Signup and view all the answers

    What is the term for short chains of amino acids containing fewer than 50 amino acids?

    <p>Peptides</p> Signup and view all the answers

    What is the level of protein structure that is dependent on the tertiary structure of individual polypeptides?

    <p>Quaternary structure</p> Signup and view all the answers

    What is the role of the four calcium ions in thermolysin?

    <p>Stabilization of the enzyme's thermal stability</p> Signup and view all the answers

    Which type of amino acid residues are resistant to heat cleavage by trypsin and chymotrypsin?

    <p>Non-polar R groups</p> Signup and view all the answers

    What is the function of CNBr in protein chemistry?

    <p>Methionine-specific cleavage of peptide bonds</p> Signup and view all the answers

    What is the purpose of hydrazinolysis in protein chemistry?

    <p>Qualitative identification of C-terminal amino acids</p> Signup and view all the answers

    What is the primary structural component of all tissues in humans and other animals?

    <p>Proteins</p> Signup and view all the answers

    What are proteins composed of?

    <p>Amino acids linked together</p> Signup and view all the answers

    What is the term for the region of the enzyme molecule where the substrate binds?

    <p>Active site</p> Signup and view all the answers

    What is the term for the substance that an enzyme acts on in a reaction?

    <p>Substrate</p> Signup and view all the answers

    What is the term for an enzyme without its non-protein moiety?

    <p>Apoenzyme</p> Signup and view all the answers

    What type of cofactor is loosely bound to an enzyme by non-covalent bonds?

    <p>Coenzyme</p> Signup and view all the answers

    What is the term for the complex formed when a substrate binds to an enzyme?

    <p>Enzyme-substrate complex</p> Signup and view all the answers

    What type of cofactor is tightly bound to an enzyme by covalent bonds?

    <p>Prosthetic group</p> Signup and view all the answers

    What is the primary function of gel electrophoresis in protein analysis?

    <p>To separate and identify protein fragments based on their sizes</p> Signup and view all the answers

    Which reagent reacts with the N-terminus of an amino acid?

    <p>Cyanogen bromide (CNBr)</p> Signup and view all the answers

    What is the specific function of trypsin in proteolytic cleavage?

    <p>Cleaves at the peptide bond on the carboxyl side of arginine and lysine</p> Signup and view all the answers

    What is the purpose of using papaya (papain) in meat tenderization?

    <p>To break down collagen in meat through enzymatic action</p> Signup and view all the answers

    Which of the following is NOT a function of chymotrypsin?

    <p>Cleaves at the peptide bond on the carboxyl side of arginine and lysine</p> Signup and view all the answers

    What is the reaction mechanism of Dansyl chloride with amino acids?

    <p>It reacts with primary amino groups in aliphatic and aromatic amines to produce stable blue- or blue-green–fluorescent sulfonamide adducts</p> Signup and view all the answers

    What is the biochemical activity of the enzyme catalase?

    <p>Transfer a functional group between donor and acceptor molecules</p> Signup and view all the answers

    Which type of enzyme catalyses the reaction of joining two molecules with covalent bonds using energy from ATP?

    <p>Ligases</p> Signup and view all the answers

    What is the biochemical activity of transaminases such as ALT and AST?

    <p>Transfer a functional group between donor and acceptor molecules</p> Signup and view all the answers

    Which of the following enzymes is an example of a phosphotransferase?

    <p>Kinase</p> Signup and view all the answers

    What is the biochemical activity of the enzyme phenylalanine hydroxylase?

    <p>Transfer a functional group between donor and acceptor molecules</p> Signup and view all the answers

    Which of the following enzymes is an example of a lyase?

    <p>Fumarase</p> Signup and view all the answers

    Study Notes

    Amino Acids and Proteins

    • There are 20 different types of amino acids that constitute the monomer units of proteins.
    • Amino acids are linked together by peptide bonds to form chains, which can be classified as peptides (short chains, fewer than 50 amino acids) or polypeptides (longer chains).
    • Each protein has its own unique combination of amino acids.

    Protein Structure

    • Proteins have unique shapes due to bonding arrangements, including:
    • Peptide bonds (primary)
    • Hydrogen bonding (secondary and tertiary)
    • Ionic attraction/bonds (tertiary)
    • Hydrophobic and hydrophilic interactions (tertiary)
    • Covalent sulfur bonds (tertiary)
    • Quaternary structure is dependent on the tertiary structure of individual polypeptides and is influenced by these bonds.

    Protein Denaturation

    • Proteins can be denatured by:
    • Heat
    • Mechanical agitation
    • Detergents
    • Organic compounds
    • pH changes
    • Inorganic salts

    Enzymes

    • Enzymes are proteins that increase the rate of reaction by lowering the energy of activation.
    • They catalyze nearly all chemical reactions in the body's cells.
    • Enzymes are not altered or consumed during reaction.
    • Example: Thermolysin, a thermostable zinc endopeptidase, contains zinc and four calcium ions necessary for its thermal stability.

    Enzyme Structure and Function

    • The active site is the area on the enzyme where the substrate or substrates attach.
    • Enzymes contain a special pocket or cleft called the active site.
    • Apoenzyme is an inactive enzyme without its non-protein moiety, while holoenzyme is an active enzyme with its non-protein component.
    • Cofactors are non-protein chemical compounds bound to an enzyme, required for catalysis.
    • Types of cofactors include coenzymes and prosthetic groups.

    Enzymatic Reactions

    • Substrate is the substance at the beginning of the enzymatic reaction.
    • Enzyme-substrate complex forms when the substrate binds to the enzyme.
    • Examples of enzymes include lactate dehydrogenase, glucose oxidase, and peroxidase.

    Biochemical Activity

    • Transferases: transfer functional groups between donor and acceptor molecules.
    • Hydrolases: catalyze the hydrolysis of various bonds.
    • Lyases: cleave various bonds by means other than hydrolysis and oxidation.
    • Isomerases: catalyze isomerization changes within a single molecule.
    • Ligases: join two molecules with covalent bonds using energy from ATP.

    Chemical Methods

    • Proteolytic enzymes: cleave polypeptides into smaller fragments.
    • Cyanogen bromide (CNBr): cleaves at methionine residues.
    • Dansyl chloride: reacts with primary amino groups to produce stable blue- or blue-green-fluorescent sulfonamide adducts.
    • Other chemical methods: BNPS-skatole, formic acid, hydroxylamine, and 2-nitro-5-thiocyanobenzoic acid (NTCB).

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    Related Documents

    Proteins and Enzymes PDF

    Description

    This quiz covers various techniques used in protein analysis, including enzymatic cleavage, gel electrophoresis, and Dansyl Chloride. Learn how to break down polypeptides into smaller fragments and analyze them using these methods. A great resource for biochemistry and molecular biology students!

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