Amino Acids Flashcards
amino acid general formula
H
H2N-C-COOH
R
why can amino acids (except glycine) form optical isomers
they contain a chiral centre so atoms can be arranged in 2 different ways in space (2 enantiomers)
they are non-superimposable mirror images
glycine
H
H2N-C-COOH
H
serine
H
H2N-C-COOH
CH2OH
alamine
H
H2N-C-COOH
CH3
glycine at low pH
H
H3N+-C-COOH
H
glycine at high pH
H
H2N-C-COO-
H
zwitterion
species containing a positive and a negative charge
why can glycine act as a zwitterion
an internal transfer of a proton from the carboxylic acid end to the amine end allows for two opposing charges on the same species
why amino acids are solid at room temp.
when they act as zwitterions they are held together by strong electrostatic attractions between oppositely charged ends of the species
why amino acids dissolve readily in water
due to strong attractions between polar water molecules and zwitterions
peptide link
O
||
C-N
|
H
primary structure of amino acids
sequence of a chain of amino acids held together by covalent bonds
secondary structure of amino acids
alpha helix / beta pleated structure held by hydrogen bonding
tertiary structure of amino acids
arrangement of secondary structures in space held by hydrogen bonding
