KA2 - Part C Flashcards
Different R groups
- Basic (positively charged)
- Acidic (negatively charged)
- Polar
- Hydrophobic
What does the R group do?
The R group gives the amino acid its unique chemical properties and specific shape
Basic Amino Acids
Generally have a NH2 on the R group
This allows them to accept a proton (H+) and become positively charged (NH3+ if formed) and strongly hydrophilic as a consequence.
Acidic Amino Acids
Have a COOH on the R group.
This allows them to donate a proton (H+) to another atom (forming COO-). They become negatively charged and strongly hydrophilic as a consequence.
Polar Amino Acids
Hydrophilic as they form weak hydrogen bonds with each molecule.
Typical polar groups OH, C=O and NH.
Hydrophobic Amino Acids
Water hating - can’t form hydrogen bonds with water.
Possesses a H for its R group.
R group DOES NOT contain OH, COOH, NH2 or SH.
Don’t become charged.
Modulator
Ligand that can alter the activity of an allosteric enzyme
Positive and Negative Modulator
Positive - increases enzyme affinity for the substrate, increasing enzyme activity.
Negative - reduces the enzyme affinity for the substrate, reducing enzyme activity.
Primary protein structure
The primary sequence of a protein is the order in which the amino acids are synthesised during translation into the polypeptide.
Secondary protein structure
Hydrogen bonding along the backbone of the protein strand results in regions of secondary structure:
~alpha - helices
~beeta pleated sheets
~turns
Alpha helices
Twists around into a spiral with the R groups sticking outwards. Forms when hydrogen bonds form between every forth peptide bond.
Beeta pleated sheets
Created when hydrogen bonds form between parts of the polypeptide strand which run next to each other, forming a sheet.
Usually antiparallel, could be parallel.
Turns
Reverse the direction of a polypeptide chain
