MOD 2 L2 Flashcards
how many species of tRNA
20
proteins can be described in four ways
▫ Primary
▫ Secondary
▫ Tertiary
▫ Quaternary structure
the sequence of the amino acids in the chain and the disulfide links.
PRIMARY
arrangement of amino acids
SEQUENCE
peptide bond
PRIMARY
structure formed by hydrogen bonding. Examples are α-helix and β-pleated sheet.
SECONDARY
complete 3-D conformation
TERTIARY
association of two or more peptide chains to form protein.
QUATERNARY
not all amino acids undergo this structure. only hemoglobins
QUATERNARY
linear sequence of amino acids
PRIMARY
units of secondary structure
α-helix β-sheet β-turns loops
SECONDARY STRUCTURE
associations of secondary structure
α-α, β-α-β, greek key, helix-loop-helix
SUPERSECONDARY STRUCURE
units of tertiary structure
all alpha, all beta, α/β, αβ
DOMAIN STRUCTURE
FOLDS OR MODULES
associations of domain structures
multidomain (mosaic) or single domain
TERTIARY STRUCTURE
association of tertiary structure
two or more polypeptides each polypeptide a subunit
QUATERNARY STRUCTURE
The primary structure of a protein is its linear sequence of amino acids and the location of any ____
DISULFIDE BRIDGE
The primary structure of a protein is defined by the
sequence of amino acids
the sequence of amino acids forms the
PROTEIN
each component amino
acid
“residue” or “moiety”
number of amino acids
number of residues
describes the way that the chain of amino acids folds itself due to intramolecular hydrogen bonding.
SECONDARY STRUCTURE
Two common secondary structures
α-helix
β-sheet
how long is the typical α-helix
11 amino acids long
how many residues/turn in α-helix
3.6
Amino acids such as A, D, E, I, L and M (small aminoa acids) favor the formation of
α-helices
favor disruption of the helix (producing a bend)
G & P
The ____ is important as it introduces additional folding of the polypeptide backbone to allow the formation of globular proteins.
DISRUPTION OF THE HELIX
1 complete rotation
0.54 nm
3.6 residues
Cα-N bond is termed
phi angle
phi Φ angle
-57º
CO-Cα bond is termed
psi angle
psi ψ angle
-47º
fibrous protein whose structure is nearly entirely α-helical
KERATIN
a globular, flexible molecule whose structure is approximately 80% α-helical.
HEMOGLOBIN
responsible for the formation of H-bonding
BETA PLEATED SHEET
- Composed of 2 or more different regions of stretches of at least 5-10 amino acids.
- Stabilized by H-bonding between amide N’s and carbonyl C’s.
- H-bonding residues are present in adjacently opposed stretches of the polypeptide backbone.
BETA PLEATED SHEET
same direction
PARALLEL
different direction
anti-parallel
When the H-bonds are formed between the polypeptide backbones of separate polypeptide chain, they are termed
INTERCHAIN BONDS
The H-bonds of a β-sheet formed by a single polypeptide chain folding back on itself are termed
INTRACHAIN BONDS
Found in both fibrous and globular proteins
β-sheet protein
composed of twisted β-pleated sheet fibrils whose 3D structure is identical to that of silk fibrils.
AMYLOID PROTEIN
are regions that contain residues beyond the minimum number necessary to connect adjacent regions of secondary structure.
LOOPS
refer to short segments of amino acids that join two units of secondary structure
TURNS & BENDS
involves 4 aminoacyl residues, in which the 1st residue is H-bonded to the 4th, resulting in a 180° turn.
β turn
are often present in β turns
PROLINE & GLYCINE
Also known as Structural motifs
SUPERSECONDARY STRUCTURES OR FOLDS
- maintains the three dimensional shape of the protein (give shape to the secondary structure).
- The amino acid chain (in the helical, pleated or random coil form) links itself in places to form the unique twisted or folded shape of the protein.
TERTIARY STRUCTURE
ways to stabilize its tertiary shape
disulfide bridges formed when two cysteine molecules combine in which the –SH groups are oxidized
COVALENT BONDING
ways to stabilize its tertiary shape
between polar groups on the side chain.
HYDROGEN BONDING