Lecture 5 - 3-D Structure of Proteins Flashcards
What is responsible for hydrogen bonding within proteins?
-Amino groups (NH3) -Carbonyl groups (COOH)
The carbons of an AA that lie on either side of the chiral carbon
alpha-Carbon
Alpha-carbons are on same side of the amino acid
Cis
Alpha-carbons on opposite side of the amino acid
Trans
Bond between Nitrogen and chiral carbon
phi
Bond between chiral carbon and carboxylic acid group
psi
Linear arrangement of AA residues
primary structure
Coiling and/or pleating of amino acid chain
secondary structure
Alpha helices work to stabilize proteins by _____
Hydrogen bonds
Number of amino acids per turn in alpha helix
3.6
In beta strands, when one AA hydrogen bonds with only one other AA, it is a (parallel/anti-parallel).
Anti-parallel
In beta strands, when one AA residue hydrogen bonds to two other AA residues, it is (parallel/anti-parallel)
parallel
Specific 3-D configuration of a peptide chain
Tertiary structure
Bonding between cystiene residues, works to stabilize proteins by covalent linkage
Di-sulfide bonds
The structure of most “structural proteins”
Filamentous (F-proteins)
The structure of most enzymes
Globular (G-proteins)
Multiple subunit proteins coming together, often after post-translational modification
Quaternary structure
How are subunits held together in quaternary structure???
NON-covalent linkages!!!!
What is the repeating motif in collagen?
-Gly-X-Y-Gly-X-Y-
Why is repeating Gly in collagen important?
Allow for small, tight protein turns; it can be compacted
Clinical correlation: what is the mechanism behind “scurvy?”
A defective Proline hydroxylase prevents -OH from being added to Proline, this produces the inability to form collagen, which results in poor wound healing/destroyed connective tissue
Breaking of disulfide bonds
protein denaturation
What are the steps of protein denaturation?
Increased heat produces most of the denaturation; chemical denaturation breaks di-sulfide bonds
What are the three main denaturing agents?
- Urea - Beta-mercaptoethanol - Guanidinium chloride
The ____ of a protein is formed by the amino/carbonyl connection, with side chains projecting off.
backbone
2* structure bonding
α−helix and β−turn/β−sheets
3* structure bonding
-S-S- bonding
H-bonding
metal binding
hydrophobic interaction
