Amino Acids Flashcards
Which AA are acidic? What makes them acidic? Inc. 1 letter and 3 letter abbreviations
D-Aspartic Acid, Asp
E-Glutamic Acid, Glu
The R group contains a COOH
What AA are basic? What makes them basic? Inc. 1 letter and 3 letter abbreviations
K-Lysine, lys
R-Arginine, arg
H-Histamine, his
The R group contains an amine group: NH2 for lys and arg, NH for his
What is the pKa of an acidic AA? What are the aproximate pKas of the basic AA?
acidic AA pKa ~4 basic AA: -lysine ~10 -arginine ~12 -histidine ~6.5
Out of the acidic and basic AA, which are protonated and which are deprotonated at phsyiological pH?
Aspartic Acid, Glutamic Acid, and Histidine tend to be protonated at physiological pH
Lysine and Arginine tend to be deprotonated at physiological pH
Which AA are nonpolar? Inc. 1 letter and 3 letter abbreviations
F-phenylalanine L-Leucine A-Alanine W-Tryptophan V-Valine I-Isoleucine G-Glycine
What is the simplest AA? Why?
Glycine because its R group is only H
What nonpolar AA have ring structures on their R group?
Phenylalanine and Tryptophan
Where are nonpolar AA residues typically found within a protein and why?
Found on the interior of a folded globular protein so that it doesn’t interact with water.
What are the polar AA? Inc. 1 letter and 3 letter abbreviations
S-Serine, ser T-Threonine, thr Y-Tyrosine, tyr N-Asparagine, asn Q-Glutamine, gln
What group makes the polar AA polar?
For serine, threonine, and tyrosine, an OH on the R group creates polarity
For asparagine and glutamine, the NH2 on the R group creates polarity
For the polar AA, the hydroxyl groups of serine, threonine, and tyrosine residues are often modified by the attachment of a __1__ group by a regulatory enzyme called a __2__
- phosphate
2. kinase
What does quality does the added phosphate group have when added to serine, threonine, or tyrosine?
it adds more hydrophilicity to the AA
What are the 2 sulfur containing AA and which one produces disulfide bridges? Inc. 1 letter and 3 letter abbreviations
C-cysteine, cys (contains a thiol, SH)
M-methionine, met (contains a thioether)
Out of the 2 sulfur containing AA, which one is fairly polar and which fairly nonpolar?
cysteine is fairly polar d/t SH (like an alcohol but S instead of O)
methionine is fairly nonpolar d/t thioether (like an ether but S instead of O)
Why is proline a unique AA?
it’s R group is bonded to its nonpolar side chain (amine group), creating a secondary alpha-amino group and a distinctive ring structure
What are the nine essential AA?
Lysine (K), Histidine (H), Threonine (T), Valine (V), Leucine (L), Isoleucine (I), Phenylalanine (F), Tryptophan (W), Methionine (M)
Mneumonic = FVK WHILMY
AA are amphoteric, which means AA can act as ____ or ____
acids or bases
What’s the approx. pKa of the carboxyl groups?
2
What’s the approx. pKa of the ammonium groups?
9 or 10
When the pH of a solution is less than the pKa of an acidic group, the acidic group will mostly be in its _____ form.
protonated
When the pH of a solution is more than the pKa of an acidic group, the acidic group will be in its ____ form.
deprotonated
Which functional groups have a stronger tendency to donate protons, carboxyl groups or ammonium groups?
carboxyl groups
All AA have an amino group that acts as a(n) __1__ and a carboxyl that acts as a(n) __2___
- base
2. acid
