Topic 2 Flashcards
Amino Acids
structure of amino acid
carboxyl group amino group alpha-carbon center hydrogen variable side chain
chirality
alpha-carbon bound to 4 different groups; all amino acids are chiral except glycine
amphoteric
ability to react as an acid or base due to carboxyl and amino groups
peptide bonding
when he carboxyl group of one molecule reacts with the amino group of another, releasing water
stereoisomerism
when two molecules have the same atoms, but arranged differently spatially.
human amino acid stereoisomerism
only the L-amino acids are used to make proteins
amino acid classification
polar/non-polar
aromatic
+/- charged
hydrophobic/philic
non-polar R-groups
glycine alanine proline valine leucine isoleucine methionine
aromatic R-groups
phenylalanine
tyrosine
tryptophan
histidine (?)
polar uncharged R-groups
serene threonine cysteine asparagine glutamine
polar (+) R-groups
lysine
argentine
histidine
polar (-) R-groups
aspartate
glutamate
branched chain R-groups
valine
leucine
isoleucine
acidic R-groups
aspartic acid/aspartate
glutamic acid/glutamate
alkaline R-groups
lysine
arginine
histidine
amide R-groups
asparagine
glutamine
hydroxyl R-groups
serine
threonine
tyrosine
achiral R-group
glycine
hydrophilic R-groups
all of the polar groups
sulfur R-groups
cysteine
methionine
zwitterion
predominates at neutral pH
amphoteric
isoelectric pH (pI)
pH at which net charge is 0
titration of amino acids importance
net charge of the molecule at various ionic environments which has implication on
- biochemical reaction characteristics at various ionic conditions that may occur at different situations arising from normal reactions
- three dimensional spatial orientation of the molecule to interacted with another
- development of certain diseases
amino acid polymerization
condensation reaction forming a peptide bond
protein interactions
functional groups of molecules can interact with amino acid side chains and produce hydrogen bonds
modification of amino acid R-group structure
- regulate biochemical functions
- form signaling molecules
- helps in targeting or anchoring to membrane
- enhance protein-protein interactions
covalent modification of amino acid structures
hydroxylation: pro, lys
carboxylation: glu
methylation
acetylation: lys
phosphorylation: ser, thr, tyr
carb moieties
lipid moieties
O-glycosylation
carb moieties
serine
threonine
tyrosine
N-glycosylation
carb moieties
asparagine
lipid moieties
cysteine
glycine
uncommon amino acid modifications
4-hydroxyproline 5-hydroxylysine 6-N-methyllysine γ-carboxyglutamate selenocysteine
