peptide formation + structure Flashcards
stereochemistry of peptide bond
trans
true structure of peptide bond
resonance hybrid
which is stronger, peptide or single bond
peptide
which is longer, peptide or single bond
single
protein function
proteins accelerate thousands of biochemical reactions in the cell
catalysis
examples of proteins involved in catalysis
rubisco (photosynthesis)
hexokinase (first enzyme in glycolysis)
most abundant protein in earth
rubisco
first enzyme in glycolysis
hexokinase
protein function
some proteins provide protection and support
structure
ex of proteins for structure
collagen (connective tissue), elastin (elastic fibers), keratin (hair)
protein function
proteins are involved in all cell movements and muscle contraction
movement
– movement of sperm and protozoa
*dynein
protein function
various proteins have protective functions
Defense -
ex proteins for defense
keratin
immunoglobulins
protein function
various proteins regulate cellular processes
- Regulation –
ex proteins for transport
glucose transporter
hemoglobin
LDL and HDL
transferrin
storage proteins containing 20 AA
Casein and ovalbumin
example of proteins for toxin
plant lectins, venom of snake
protein structure
the order or sequence of amino acids in the polypeptide chains
*Peptide bond is a covalent bond
primary
protein structure
conformation of the polypeptide backbone
2ndary
protein structure
arrangement in space of all atoms in the polypeptide chain
tertiary
protein structure
describes the interaction of the subunits in an oligomeric protein
*stabilized by both covalent & non-covalent forces
quaternary
levels of protein structure stabilized by covalent and non-covalent forces
quaternary and tertiary
has *intersubunit interaction
quaternary
has intrasubunit interaction
tertiary
what proteins have quaternary structure
only oligomericproteinswith ≥ 2 subunits
e.g. dimer
stabilizing force of secondary structure
H-bonding between the amide proton and carboxyl oxygen
the sequence of amino acids linked by peptide bonds.
▪ The backbone of a peptide chain or protein.
primary structure
Proteins are composed of ___ only
L-amino acids
conformation of the polypeptide backbone (stabilized by H-bonding) without side chains
secondary
which is stronger? H bond or peptide
Peptide bonds
– combination of α-helix & β-pleated sheet
random coil
The backbone can change direction by making __
reverse turn and loops.
type of secondary structure
Backbone coils into a periodic/repeating, compact structure (rigid)
alpha-helix
H-bonds of alpha helix are typically ____ (olarity)
amphiphilic
is alpha helix left-handed or right handed
right handed
is a “helix-breaker”
- no more H in Nitrogen of _____; no more H-bonding
- cannot rotate freely at ф
proline
a helix breaker
due to too much flexibility of H atom in _ H atom is too small
glycine
- Polypeptide backbone is almost fully extended.
β-pleated sheet (Zigzag)
≥ 2 backbones aligned for H-bonding
β-pleated sheet (Zigzag)