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Chapter 19 Amino Acids and Proteins
Learning Objectives:
1. Draw the structure for an amino acid.
2. Write the ionic form of an amino acid.
Provide both IUPAC and common names for alcohols, phenols, ethers and thiols.
2. Recognize the physical properties of alcohols, phenols, ethers and thiols.
3. Write the dehydration equations of alcohols and predict the major product when
applicable.
4. Recognize the oxidation and reduction of alcohols and predict the products from
oxidation of primary and secondary alcohols.
5. Recognize the oxidation and reduction of thiols.
Sections:
19.1 Proteins and Amino Acids
19.2 Amino Acids as Acids and Bases
19.3. Formation of Peptides
19.4 Protein Structure: Primary and Secondary Levels
19.5 Protein Structure: Tertiary and Quaternary Levels
19.6 Protein Hydrolysis and Denaturation.
Recommended additional problems
19.47, 19.57
19.1 Proteins and Amino Acids
A. General structure
H
C
HN
Cc
OH
B. Amino acid stereoisomers
CHO CHO
—- as
CH,0H CH,0H
CO2H CO2H
HeN H H NH>
CH CH3
H2N CO2H
19.2 Amino Acids as Acids and Bases
A. Zwitterion
oO Oo
|»
®
H,N——CH—C——OH HN CH C—O
R R
6 7 9 1
C— NH,
5
Oxytocin
Vasopressin
Timberlake, General, Organic, and Sioiegiaet Chemisty, Copyright @-Peareon Education Inc., guoliehing 2x Banjamin Cummalnge.
B. Secondary structure (a helix and B sheet)
@ o helix
i Peptide
backbone of
primary structure _
@ Carbon
@ Oxygen
@ Nitrogen “Hydrogen bands of
@ 8 group secondary structure -_
@ Hydrogen
Gi) 8 sheet
“Uydrog
between peptl
(iii) Collagen
Tripte helix 3 a-Helix peptide chains
. Consists of three alpha helix chains woven together.
= Contains large amounts glycine, proline, hydroxy proline, and hydroxylysine that
contain —OH groups for hydrogen bonding.
= Is found in collagen, connective tissue, skin, tendons, and cartilage
19.5 Protein Structure: Tertiary and Quaternary Levels
A. Cross-links in tertiary structures
(i) hydrophobic interactions
Gi) hydrophilic interactions
(iii) salt bridge
(iv) hydrogen bonds
(v) disulfide bonds
oH
Hydrophilic Hi,
interaction a ¢ 2D
to water Gas de
Pia Helix
2 :
a
Hydregen bond,
;
Hydrophobic ©)
interaction @ CH,
A | Disulfide $
f $s
bonds $
* Goma
Be ented sheet
ga Sa ac
; 9
"
Hydrogen bond
‘Timberlake, Ganerst, Grgsnio, 2nd Biatogiaal Chemielry. Conpright i Pearson Education Ine. publishing as Benjamin Cummings
