BIOCH200 Lecture Notes - Lecture 11: Cysteine, Cystine, Chief Operating Officer
5 May 2018
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Hydrophobic Amino Acids
❏Lack reactive functional groups
❏No pKa values → non-ionizable as pH changes
❏8 Amino Acids
❏Most Amino Acids are Chiral
Alanine (Ala)
a. Aliphatic and Hydrophobic
b. Involved in Hydrophobic Interactions
c. Soluble (due to COO- and NH3+ on the backbone structure).
Valine (Val)
a. Aliphatic and Highly Hydrophobic (more CH3 than Ala)
b. Hydrophobic interactions
Leucine (Leu)
a. Aliphatic and Hydrophobic
b. Hydrophobic Interactions
Isoleucine (Ile)
a. Aliphatic and highly hydrophobic
b. Hydrophobic Interactions
Phenylalanine (Phe)
a. Aromatic → absorbs UV weakly at 280 nm.
b. Highly hydrophobic → Participates in hydrophobic interactions
Tryptophan (Trp)
a. Aromatic → Heterocyclic and absorbs strongly at 280 nm.
b. Hydrophobic (bulky) → Participates in Hydrophobic interactions.
c. H-bond Donor.
Methionine (Met)
a. Hydrophobic → Participates in Hydrophobic interactions
b. Not a true aliphatic due to sulfur
c. Sulfur Hydrogen bonds → 2 acceptors.
d. Sulfur containing → thioether (C-S-C)
Proline (Pro)
a. Aliphatic Side Chain → distinctive cyclical structure
b. Hydrophobic → hydrophobic interactions.
Polar Amino Acids
❏Have electronegative atoms
❏Reactive due to the presence of functional groups
❏Tyr, Cys and His have ionizable R groups.
❏8 Amino Acids
Glycine (Gly)
a. Smallest Amino Acid that is also achiral → Flexible
b. Weakly polar
Serine (Ser)
a. Polar and uncharged → Contains OH group
b. Hydrogen bonding → 1 donor and 2 acceptors
c. Phosphorylate → Add phosphate to OH to make bigger and charged structure
Threonine (Thr)
a. Polar uncharged → Contains OH group
Document Summary
No pka values non-ionizable as ph changes. Valine (val: aliphatic and hydrophobic b, soluble (due to coo- and nh3+ on the backbone structure). Involved in hydrophobic interactions: aliphatic and highly hydrophobic (more ch3 than ala, hydrophobic interactions. Leucine (leu: aliphatic and hydrophobic, hydrophobic interactions. Isoleucine (ile: aliphatic and highly hydrophobic, hydrophobic interactions. Phenylalanine (phe: aromatic absorbs uv weakly at 280 nm, highly hydrophobic participates in hydrophobic interactions. Proline (pro: aliphatic side chain distinctive cyclical structure, hydrophobic hydrophobic interactions. Reactive due to the presence of functional groups. Tyr, cys and his have ionizable r groups. 8 amino acids: smallest amino acid that is also achiral flexible, weakly polar. Serine (ser: polar and uncharged contains oh group, hydrogen bonding 1 donor and 2 acceptors, phosphorylate add phosphate to oh to make bigger and charged structure. Threonine (thr: polar uncharged contains oh group, hydrogen bonding 2 acceptor and 1 donor, can be phosphorylated (add phosphate)
