Amino Acid Reactions

Question 1

What are the enzymes responsible for catalyzing peptide bond hydrolysis?

Answer 1

Proteases

Question 2

What kind of conditions can catalyze peptide bond hydrolysis?

Answer 2

Strongly acidic conditions

Question 3

What are peptide bonds?

Answer 3

Bonds that join amino acids together to form peptide chains. Peptide bonds are formed between the carboxylic acid group of one amino acid and the amine group of another. Form an amide.

Question 4

What is a condensation reaction?

Answer 4

It is bond synthesizing and releases H20. The amine loses a hydrogen atom and the carboxylic acid loses a hydroxyl group (-OH)

Question 5

What is nucleophilic substitution?

Answer 5

When a leaving group is replaced by an electron rich compound. It is often seen in reaction involving carboxylic acid derivatives.

Question 6

What is hydrolysis?

Answer 6

Bond breaking by adding H2O. It is energetically favorable but extremely slow under physiological conditions.

Question 7

What are proteases?

Answer 7

They are the enzymes responsible for catalyzing peptide bond hydrolysis. They destroy primary structure of a protein.

Question 8

What is pepsin?

Answer 8

A type of protease (enzyme) that breaks down proteins in foods.

Question 9

When peptide bonds show resonance where are the positive and negative charges found?

Answer 9

The oxygen is negatively charged and the nitrogen is positively charged.

Question 10

What does the partial double bond character between the carbon and nitrogen atom lead to.

Answer 10

It gives the peptide chains a planar conformation. Therefore, peptide bonds do not rotate freely. This also helps contribute to the structural stability of the 3D polypeptide structure.

Question 11

How are peptide bonds formed and broken?

Answer 11

By nucleophilic substitution.

Question 12

Define nonessential amino acids and name these amino acids.

Answer 12

These amino acids are synthesized by the human body so we do not need to consume them in our diet.
A,D,N,E, and S

Question 13

Define essential amino acids and name these amino acids.

Answer 13

These amino acids are NOT synthesized by the human body so we need to consume them in our diet.
H,I,L,K,M,F,W,V,R,C,G,Q,P,Y, and T

Question 14

What are the two lab based ways to synthesize amino acids in a selective way?

Answer 14

The Strecker Synthesis and the Gabriel Synthesis. The alpha amino acid is the basic output for both but are very distinct processes.

Question 15

What are the simple steps of the Strecker Synthesis?

Answer 15

1. Convert the carbonyl group on the
   aldehyde to an amine. (using NH4Cl)
2. Add nitrile group (using KCN), which
   provides an extra carbon and a scaffold in
   the form of a triple bond for subsequent
   addition of water.
3. Keep adding water (or H3O+) to the triple
   bond and shuffling protons around until
   the amine can be kicked out to generate
   a carboxylic acid.

Question 16

What are the simple steps of the Gabriel Synthesis?

Answer 16

1. Begins with very protected nitrogen atom,
   most likely in phthalimide.
2. Deprotonate nitrogen atom
3. Halide is kicked off of alkyl halide (Malonic
   ester), and alkyl chain is added to the
   nitrogen atom.
4. Use hydrazine or H3O+ to free nitrogen
   atom to form primary amine (hydrazine
   results in phthalhydrazide (NH) and H3O+
   yields phthalic acid (OH).
5. Decarboxylation occurs once heat is
   added (CO2 is released)

Question 17

What are dipeptidases also known as?

Answer 17

Proteases. They catalyze the breaking of links between two amino acids.