Flashcards in Amino Acids The Building Blocks of Proteins Deck (18):
Generic Amino Acid
- alpha-amino group bonded to a the alpha carbon
- alpha carbon covalently bonded
- alpha-carboxyl group bonded to alpha carbon
- N termini to C termini
In terms of epigenetics
- modify Lys and arg residues
- modifications of histones
Hydrophobic (neutral) R groups
- R groups are all hydrocarbons
- interact with each other, lipid surfaces, or other hydrophobic groups (bases in nucleic acids)
- do not react well with H2O
Hydrophilic (neutral) R groups
- partial charges
Acidic R groups
- have full negative charges
Basic R groups
- have full positive charges.
Acid and Basic R groups
- have full charges due to polar covalent bonds resulting in unequal sharing.
The distinction between hydrophobic and hydrophilic
- is not sharp.
- there is complete gradation between very hydrophobic and very hydrophilic.
- help predict structure of proteins using gradation
Aromatic Amino Acids
- 6 membered ring
- absorb near UV light
- conjugated, alternating double bonds.
- Phenylalanine, Tyrosine, Tryptophan
The aliphatic amino acids
- not aromatic.
Cysteine cross-linking proteins in reduced form
- The sulfhydryl groups are separate on each backbone
Cysteine cross-linking proteins in oxidized form
- involved in cross linking proteins
- crosslinks two separate proteins or different regions of the same protein.
- H2O is released
- stabilizes the 3D structure of proteins
Modification of amino acids with R groups that contain hydroxyl groups
- commonly modified by phosphorylation
- in post translational modification (after being incorporated into proteins)
- gives it a full negative charge
- how cells change the properties of proteins
- H2O is released.
Lysine post-translational modification
- on epsilon amino group
- addition of an acetyl group on epsilon amino group
- charge lost
- addition of methyl group on epsilon amino group
- charge not lost.