Properties of Protein Functional Groups Flashcards
What are Zwitterions
Dipolar ions that are still net neutral
What makes it a weak acid or base?
Weak acids/bases favor “HA” over dissociated while a strong acid or base dissociates virtually completely. Weak acids can use the Henderson-Hasselbalch equation while strong acids and bases use the simple equation.
What is a buffer’s range?
The ratio of conjugate base to weak acid that doesn’t result in change in [H+] greatly changing pH. Usually +/- 1 pKa
What is a buffer’s capacity?
The amount of protons that can be added or removed without shift in pH
What defines isoelectric point?
pH at which net charge of amino acid is 0 = average of pKa’s
Side chain functional group and class of Lysine
Amino - charged
Side chain functional group and class of Arginine
Guanidino - charged
Side chain functional group and class of Histidine
Imidazole - charged
Side chain functional group and class of aspartic acid
Carboxyl - charged
Side chain functional group and class of glutamic acid
Carboxyl - charged
pKa of Lysine
10
pKa of Arginine
12
pKa of Histidine
6
pKa of Glutamic Acid
4
pKa of Aspartic Acid
4
Unique property of charged amino acids
Can form salt bridge
Unique characteristics of nonpolar amino acids
London Dispersion and Hydrophobic effect are major force of interaction/structure
Side chain functional group and class of Glycine, Alanine, Valine, Leucine, Isoleucine
Alkyl - non-polar
Side chain functional group and class of Methionine
Thioether - nonpolar
Side chain functional group and class of Proline
Intra-residue pyrroline - nonpolar
Side chain functional group and class of Phenylalanine
Phenyl - nonpolar
Side chain functional group and class of Tryptophan
Indole - nonpolar
Unique characteristics of polar amino acids
Primary bonding by dipole-dipole or hydrogen bonding - interacting with other polar side chains
Side chain functional group and class of Threonine and Serine
Hydroxyl - polar