proteins lec 1 Flashcards
Amino acids contain
carboxyl and amino termini
In ___ the __ carbon is denoted the ___
amino acids
central
alpha carbon
amino acids are ___ in equilibrium with Zwitterion ions and non-ionic form
acids
charges
N terminus?
C terminus?
N = positive C= negative
most/some amino acids exhibit ___ (almost exclusively ___ acids on earth)
most
chirality
L-amino
types of amino acids in proteins
20
amino acids contain a variable ____ denoted __
side chain
R
Polar side chains vs non-polar side chains
Polar side: hydrophilic form hydrogen bonds with -OH groups form C= O bonds form NH2 bonds
Non-polar:
hydrophobic
contains lots of carbons
includes glycine (nonchiral)
example of polar/non-polar side chains that form hydrogen bonds with -OH groups
polar
Ser
Thr
Tyr
Which type of sidechain forms C=O bonds
Polar
Asn
Gin
Which type of sidechain forms NH2 bonds
Polar
Asn
Gin
Which type of sidechain is found inside protein molecules
non-polar
Which amino acid of the polar/non-polar side chain is nonchiral
non-polar
glycine
All amino acids except ____ are chiral? True or false
glycine
True
types of amino acid side chains
3
nonpolar
polar
electrically charged
Electrically charged side chains
hydrophilic
basic side chains/positively charged (Lys, Arg, His)
acidic side chains/negativity charged (Asp, Glu)
charged or not depends on environment pH
Asp and Glu are ___ charged
negatively
Lys, Arg, His are _____ charged
positively charged
Acid/base properties
when pH = pK, there are ___ amounts of ___ and _____ amino acid forms
equal
protonated
deprotonated
amino acids are acids in ____
equilibrium with zwitterion and non-ionic forms
if pH is greater than the pKa of the amino acid, there will be more ____ forms (_______)
de-protonated
shifting of the equilibrium
histidine changes ___ slightly depending on the environment
pKa
at ~7 Asp, Glu, Lys, Arg fare usually negative/positive
Asp- negative
Glu -negative
Lys - positive
Arg - positive
what property of Glycine allows it to be flexible
size : small
what forms disulphide linkages (-SH groups form -S-S-)
cysteine
____ gives rigidity (introduces kinks to proteins)
proline
problem with viruses eg ____ ? Solution?
HIV
The HIV surface protein amino acid sequences keep changing therefore we can’t make conventional vaccines to combat it
Target HIV enzymes for inhibition
