30 Questions
What is the purpose of using 1-fluoro-2-4-dinitrobenzene (DNB) or Sanger Reagent?
To identify the first amino acid in a polypeptide chain
What is the outcome of using Sanger Reagent under acid conditions?
The breaking of bonds in the polypeptide chain
What is the advantage of using Edman Degradation over Sanger Reagent?
It does not break the bonds in the polypeptide chain
What is the result of using Sanger Reagent repeatedly?
The determination of the entire sequence of the polypeptide
What is the reagent used in Edman Degradation?
Phenylisothiocyanate
What is the purpose of using Thin Layer Chromatography (TLC) in protein sequencing?
To compare the Rf value of the derivative with the standard
What is the role of zinc ion in thermolysin?
Involved in the cleavage of peptides
What is a characteristic of the Lock-and-Key Model of enzyme action?
The active site has a rigid shape.
Which amino acids are resistant to heat?
Valine, Isoleucine, and Leucine
What type of bonds are cleaved by thermolysin?
Amino linked bonds of aliphatic amino acids
What is the purpose of the Enzyme-Substrate complex?
To convert the substrate to product.
What is the function of proteins in the body?
To build, maintain, and repair tissues
Which model of enzyme action is more consistent with a wider range of enzymes?
Induced-Fit Model
What is the result of the reaction within the active site of the Enzyme-Substrate complex?
The conversion of substrate to product.
What is the primary structural component of all tissues in humans and animals?
Proteins
What is the function of an enzyme in a reaction?
To increase the reaction rate.
How are proteins composed?
Composed of amino acids linked together
What is the overall reaction for the conversion of substrate to product?
E + S → ES → E + P
What happens to an enzyme at extreme temperatures?
It denatures and unfolds
What is the optimal pH range for most enzymes?
pH 6-8
What is the effect of increasing substrate concentration on the reaction rate?
The reaction rate increases
What is the role of cofactors and coenzymes in enzymatic activity?
They are sometimes needed for proper enzymatic activity
What is the effect of a competitive inhibitor on the reaction rate?
It slows down the reaction rate
What is the term for the temperature at which an enzyme's reaction rate is highest?
Optimal temperature
What is the mechanism of action of noncompetitive inhibitors?
They bind to a different site on the enzyme, causing a conformational change.
What is the naming convention for many enzymes?
They end in -ase.
How are enzymes classified by the International Union of Biochemists?
By the type of reaction they catalyze.
What is the biochemical activity of oxidoreductases?
They catalyze oxidation/reduction reactions.
What is the effect of noncompetitive inhibitors on the enzyme reaction rate?
They slow down the reaction rate.
What is the function of sucrase?
It catalyzes the hydrolysis of sucrose.
Study Notes
Thermolysin and Proteins
- Thermolysin is a thermostable zinc endopeptidase that contains a zinc ion for catalysis and four calcium ions for thermal stability.
- It cleaves peptides at amino-linked bonds of aliphatic amino acids (e.g., Val, Ile, Leu) that resist heat.
- The proposed mechanism for thermolysin-catalyzed cleavage of peptides involves the cleavage of amino-linked bonds of aliphatic amino acids.
Enzyme Function and Specificity
- Enzymes are highly specialized and have specific purposes in the body.
- Enzymes are composed of amino acids linked together.
- Enzymes increase reaction rates by decreasing the activation energy.
- Enzymes have varying degrees of specificity for substrates, recognizing and catalyzing a single substrate, a group of similar substrates, or a particular type of bond.
Mechanism of Action of Enzymes
- Enzymes increase reaction rates by decreasing the activation energy.
- Enzyme-substrate interactions involve the formation of an enzyme-substrate complex through the lock-and-key model or the induced-fit model.
- The lock-and-key model describes the active site as having a rigid shape that only allows substrates with the matching shape to fit.
- The induced-fit model describes the active site as flexible, adjusting to maximize the fit with the substrate.
Factors Affecting Enzyme Activity
- Environmental conditions, such as temperature, pH, and substrate concentration, affect enzyme activity.
- Optimum temperature, pH, and substrate concentration vary for different enzymes.
- Cofactors and coenzymes, such as inorganic substances and vitamins, are sometimes necessary for proper enzymatic activity.
Enzyme Inhibitors
- Enzyme inhibitors slow down the reaction rate by binding to the active site, reducing the enzyme's activity.
- Competitive inhibitors resemble the substrate and bind to the active site, reducing the enzyme's activity.
- Non-competitive inhibitors bind to a different location on the enzyme, causing a conformational change that slows down the reaction rate.
Learn how to identify the first amino acid in a protein sequence using chemical reactions and enzymes. This quiz covers the Sanger reagent method and its application in protein sequencing.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
