Buffers and peptides Flashcards
in pure water, [h3o+]=[oh-]=
1 times 10^-7
kw=[h+][OH-]=
10^-14 M
an increase in [H+] is always
accompanied by a decrease in [OH-]
lower pka means that group favors
deprotonation at physiological pH
hh equation
pH=pKa+log[A-]/[HA]
buffering capacity is the greatest at the _____ and most effective within
pKa, within +/- 1 pH units
changing the pH by 1 unit changes the ration of acid to conjugate base by a factor of _____
10
most common amino acids are r or s
s (except for cysteine)
isobaric isomers
leucine and isoleucone
b-branched
valine and isoleucine
pKr of tyrosine
10
nonpolar/hydrophobic
alanine, valine, leucine, isoleucine, methionine, proline, phe
arginine group
guanidinium
histidine has a ____ ring
imidazole
pka =
in terms of ka
-log10ka
lower pka means what at physiological ph
deprotonation
does a- always have negative charge
no
if pH=pKa what does that mean for wa and wb
[a-]=[ha]
what happens when ph=pka for sa or sb
a strong acid or strong base completely dissociates and neutralizes a wa or cb
smallest of the nonpolar side chains
alanine
methionine
nonpolar despite sulfar, long and flexible
pkr of tyrosine
10
aromatic amino acids absorb UV wavelengths why
conjugated pi systems give e= tranistions of the right energies
tryp is also _____ at 300-350 nm
fluorescent
___ and ____ hydroxyl groups give h bonding potential
serine and threonine
cysteine
can form weak h bonds, and good nucleophile
cysteine pkr
8
aspartate pkr
3.5
glutamate pkr
4
lysine pkr
10.5
arginine pkr
12.5
histidine pkr
6
which has indole ring
tryptophan
guanidium ring
arginine
imidazole ring
histidine
fluorescent at 300 nm
tryptophan
side chain amide groups provide even more h bonding potential
asparagine and glutamine
