lecture 3 Flashcards
molecules in one human cell percent by mass
water 65 lipids 12 protein 20 nucleic acids 1 DNA 0.1
roles of protein
transport structural scaffolds mechanical function immune response signalling catalysis
structure of amino acids
amine and carboxylic acid groups and another R group
how many naturally occuring amino acids
20
which amino acid isnt chiral
glycine
when are amino acids zwitterions
at neutral pH
what sort of reaction makes an amide peptide bond
condensation
what order do we write amino acids in
N to C terminus
what holds three dimensional structures of proteins together
hydrogen bonds van der waals and some disulphide bonds
what catalyzes the hydrolysis of amides at neutral pH
chymotrypsin half life goes from 400 years to 0.1 seconds
what are stereoisomers of amino acids referred to as
L and D enantiomers
what stereoisomer are all amino scids in the body
L-form
properties of aromatic amino acids
involved in pi-pi stacking interactions
absorb UV -A280
TRP flouresence excitation 280 nm emission 350 nm emission
is creation of disulphide bonds oxidation or reduction
oxidation
when is the amino acid half protonated half deprotonated
when the pH = pKa
