Transcript  -sheet 2 peptide backbones Very open configuration

-sheet
2 peptide backbones
Very open configuration
"Pleated"
Parallel and antiparallel
Tertiary Structure
• Thermodynamically most stable form
• Held together by
– Hydrophobic interactions
– Electrostatic interactions
– -S-S- bonds
• Can include non-protein groups
– Prosthetic groups or co-enzymes
• Determined by x-ray crystalography
Types of Tertiary Structures
• Fibrous proteins
– Silk
– Keratin
– Collagen
• Globular proteins
Quaternary Structure
Carbohydrates
(saccharides)
Monosaccharides
• Polyhydroxy aldehydes or ketones
– Aldoses—aldehyde on end
– Ketoses—ketone in chain
Monosaccharides, con't.
• Named by number of carbons
– Trioses
– Tetroses
– Pentoses
– Hexoses
– Heptoses
Glucose
• 4 chiral carbons
• "D" configuration
• Fischer projection
Ring formation
CH2OH
CHO
6
CH2OH H
H C OH
HO C H
H C OH
H C OH
CH2OH
D -glucose
H
C
HO
H
4C
HO
5C
H
OH
H
O
H
1
3C
C2
H
OH
C
H
OH
O
C
C
H
OH
H
H
C
OH
-D-glucose
C
O
CH2OH
H
C
HO
C
H
OH
O
C
C
H
OH
H
OH
C
H
-D-glucose
Chair configuration
A
H
E
E
A
CH2OH H
O
O
E
E
A
A
HO
OH
HO
H
E
A
H
OH
H
Aldohexoses
CH2OH
CH2OH
H
C
HO
C
H
OH
O
C
C
H
OH
H
-D-glucose
OH HO
C
C
H
H
C
H
OH
O
C
C
H
OH
H
B-D-galactose
CH2OH
OH H
C
C
H HO
C
H
OH
O
C
OH
OH C
H
C
H
H
B-D-mannose
Monosaccharide derivatives
COOH
CHO
H C OH
CH2OH
H C OH
HO C H
HO C H
H C OH
H C OH
H C OH
H C OH
CH2OH
COOH
D-gluconic acid
H C OH
CH2OH
H C OH
H C OH
H C OH
CH2OH
CH2OH
D-glucuronic acid
D-ribitol
CH2OH
HOH2C
OH
O
H
H
H
H
OH
H
H
C
HO
C
H
OH
O
C
C
H
N
H
glycerol
CH2OH
OH
C
H
OH C
H
C OH
H
C
H
O
H
C
OH
C
H
N
C O
C O
CH3
CH3
N-acetyl--D-glucosamine N-acetyl--D-galactosamine
Fructose
CH2 OH
C O
HO C H
H C OH
H C OH
CH2 OH
D-fructose
HOH2C
CH2OH
O
H
OH
H
-D-fructofuranose
OH
O
H
HO
H
OH
HOH2C
HO
H
CH2OH
OH
H
-D-fructofuranose
Glycosidic bonds
CH2OH
OH C
H
C OH
H
C
H
O
H
C
CH2OH
H
C
HO
OH
C
H
OH
H2O
H
C
H
OH
condensation
CH2OH
CH2OH
O
C
C
H
OH
C
H
H2O
hydrolysis
H
O
-D-glucose
-D-galactose
OH C
H
C OH
H
C
C
H
OH
C
H
O
H
C
OH
C
H
OH
O
C
C
H
OH
H
OH
C
H
Lactose
-D-galactopyranosyl-(1
4)--D-glucopyranose
Polysaccharides
Types
• Storage
– Starch
– Glycogen
• Structural
– Cellulose
– Chitin
– Extracellular matrix
Storage
• Glucose in (14) linkages
• Amylose—10-30%
– unbranched
• Amylopectin—70-90%
– Branched every 12-25 residues
– (16) linkages
• Glycogen
– Branched every 8-12 residues
Glycogen
Structural
• Cellulose
– Glucose
– (14) linkages
– No branches
– Most abundant macromolecule
Structural, con't.
• Chitin
– N-acetyl glucosamine
– Second most abundant macromolecule
• Bacterial cell wall
– peptidoglycan