First Amino Acid in a Protein Sequence Quiz and Flashcards

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Questions and Answers

What is the purpose of using 1-fluoro-2-4-dinitrobenzene (DNB) or Sanger Reagent?

To break the bonds in a polypeptide chain

To synthesize a polypeptide chain

To determine the entire sequence of a polypeptide

To identify the first amino acid in a polypeptide chain (correct)

What is the outcome of using Sanger Reagent under acid conditions?

The formation of a complex with the first amino acid

The extraction of the derivative of the first amino acid

The breaking of bonds in the polypeptide chain (correct)

The synthesis of a new polypeptide chain

What is the advantage of using Edman Degradation over Sanger Reagent?

It does not break the bonds in the polypeptide chain (correct)

It is only used for synthesizing polypeptide chains

It is faster and more efficient

It is more expensive and time-consuming

What is the result of using Sanger Reagent repeatedly?

The determination of the entire sequence of the polypeptide Signup and view all the answers

What is the reagent used in Edman Degradation?

Phenylisothiocyanate Signup and view all the answers

What is the purpose of using Thin Layer Chromatography (TLC) in protein sequencing?

To compare the Rf value of the derivative with the standard Signup and view all the answers

What is the role of zinc ion in thermolysin?

Involved in the cleavage of peptides Signup and view all the answers

What is a characteristic of the Lock-and-Key Model of enzyme action?

The active site has a rigid shape. Signup and view all the answers

Which amino acids are resistant to heat?

Valine, Isoleucine, and Leucine Signup and view all the answers

What type of bonds are cleaved by thermolysin?

Amino linked bonds of aliphatic amino acids Signup and view all the answers

What is the purpose of the Enzyme-Substrate complex?

To convert the substrate to product. Signup and view all the answers

What is the function of proteins in the body?

To build, maintain, and repair tissues Signup and view all the answers

Which model of enzyme action is more consistent with a wider range of enzymes?

Induced-Fit Model Signup and view all the answers

What is the result of the reaction within the active site of the Enzyme-Substrate complex?

The conversion of substrate to product. Signup and view all the answers

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

Proteins Signup and view all the answers

What is the function of an enzyme in a reaction?

To increase the reaction rate. Signup and view all the answers

How are proteins composed?

Composed of amino acids linked together Signup and view all the answers

What is the overall reaction for the conversion of substrate to product?

E + S → ES → E + P Signup and view all the answers

What happens to an enzyme at extreme temperatures?

It denatures and unfolds Signup and view all the answers

What is the optimal pH range for most enzymes?

pH 6-8 Signup and view all the answers

What is the effect of increasing substrate concentration on the reaction rate?

The reaction rate increases Signup and view all the answers

What is the role of cofactors and coenzymes in enzymatic activity?

They are sometimes needed for proper enzymatic activity Signup and view all the answers

What is the effect of a competitive inhibitor on the reaction rate?

It slows down the reaction rate Signup and view all the answers

What is the term for the temperature at which an enzyme's reaction rate is highest?

Optimal temperature Signup and view all the answers

What is the mechanism of action of noncompetitive inhibitors?

They bind to a different site on the enzyme, causing a conformational change. Signup and view all the answers

What is the naming convention for many enzymes?

They end in -ase. Signup and view all the answers

How are enzymes classified by the International Union of Biochemists?

By the type of reaction they catalyze. Signup and view all the answers

What is the biochemical activity of oxidoreductases?

They catalyze oxidation/reduction reactions. Signup and view all the answers

What is the effect of noncompetitive inhibitors on the enzyme reaction rate?

They slow down the reaction rate. Signup and view all the answers

What is the function of sucrase?

It catalyzes the hydrolysis of sucrose. Signup and view all the answers

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.

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Description

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.

Y1S2 003 I Biochem First Amino Acid in a Protein Sequence

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