Amino Acids

Amino Acids

Amino Acids

Amino Acids

Properties of Amino Acids• Ques. 4: Use the above structures to answer the questions below:• a. Which amino acid is most polar?• b. Which amino acid is least polar?• c. Which amino acid has an acidic side chain?• d. Which amino acid has a basic side chain?

Properties of Amino Acids• Ques. 5: Use the below structures to answer the questions:

• a. Which amino acid is most polar?

• b. Which amino acid is least polar?

• c. Which amino acid is the most polar looking at thr and ser?

• d. Which amino acid is the least polar looking at asp and glu?

Amino Acids• Zwitterion - acid and amine react with each other internally.

Amino Acids• -> -> Increasing pH -> ->

• pH << pK << pH • Acids: HA molecular A- ionic

• Bases: BH+ ionic B molecular

Amino Acids• -> -> Increasing pH -> ->

• pH << pK << pH • Acids: HA molecular A- ionic

• Bases: BH+ ionic B molecular

Amino Acids• -> -> Increasing pH -> ->

• pH << pK << pH • Acids: HA molecular A- ionic

• Bases: BH+ ionic B molecular

Amino Acids

Separations of Amino Acids

Amino Acids

• -> -> Increasing pH -> ->• pH << pK << pH

• Acids: HA molecular A-

ionic• Bases: BH+ ionic B molecular

• Mixture of val pI = 6; asp pI = 2.8, lys pI = 9.7in a buffer at pH = 6. What is the form of each?

CNCH

CHCH3H3C

O

O_+ H3

val

C

N

CH

CH2C

O

-O

O

O-H3+

asp lys

C

N

CH

CH2H2C

CH2H2C

N O

O-

H3+ H3

+

Reactions Amino Acids - Salt Formation

• Acid + amine --> salt (acid donates H+ to amine)

Reactions Amino Acids - Disulfide

• 2 thiols + (O) --> disulfide + HOH

Synthesis of a peptide• Amine + acid --> amide + HOH

Synthesis of a peptide• Amine + acid --> amide + HOH

Synthesis of a peptide• Write repeating units of backbone and add side chains