lecture 6 part 2 Flashcards
what determines function of protein
structure
what is the unique 3D folding of a protein detemrined by
amino acid sequence
what dictates molecular interactions of each amino acid
chem properties of the side chain
Vast majority of molecular interactions with amino acids are covalent or non covalent?
non covlaent
what join amino acids together
peptide bonds
how are peptide bonds formed
by dehydration rxn
where is the covalent bond of the amino acid
between carbon in carboxyl group of last amino acid and the nitrogen on the amino group of the incoming amino acid
what is peptide bond formation catalyzed by
ribosomes within a cell (ribosomes conduct dehydration rxn to form new proteins)
peptide
a few amino acids joined together
polypeptide
many amino acids joined together
what splits peptide bond
hydrolysis rxn
four levels of protein structure
1)primary structure
2)secondary structure
3)tertiary structure
4)quaternary structure
primary structure
-our polypeptide chain/sequence of amino acids -sequence begins at free amino end and is read to the carboxyl end
secondary structure
-protein folding involving portions or segments of a polypeptide chain
-two major types 1)alpha helix 2) beta-sheets
-due to hydrogen bonding by atoms in the peptide backbone secondary structure is held together
-nitrogen of amino group and the oxygen with a double bond to carbon are binding to each other
-side chains are not involved
-in both alpha helices and beta sheets, side chains face outward from the backbone
-when side chains face outward, they can interact with other parts of the folded protein or other molecules
tertiary structure
-overall folding of 3D conformation of a single polypeptide chain
-bonding by side groups are important for tertiary structure
bonds important for holding tertiary strcture in its shape are
-hydrophobic interactions
-van der waals forces
-hydrogen bonding
-disulfide bridge
-ionic bond
-polypeptide backbone
(most of the bonds holding a protein in its 3D shape are noncovalent)
where do hydrophobic side chains tend to be buried
inside a folded protein and the hydrophilic ones face outward
some proteins are composed of
a single folded polypeptide chain and others are composed of two or more polypeptide chains folded together into a final structure
example of protein composed of a single folded polypeptide chain
myglobin
example of protein composed of two or more polypeptide chains folded together into final structure
collagen
Quaternary structure
-2 or more polypeptide chains folding together to make a functional product protein
example of quaternary structure are
hemoglobin and antibodies
subunits
one poly peptide chain that is in a protein with quaternary structure
