Amino Acids, Protein Structure, and Function: Comprehensive Review for Biology

Amino Acids

makeproteins

Structure of Amino acids (4)

1. α amino group 2. α carboxyl group 3. α carbon 4. side chain R group

Chiral

4 different groups attached to α carbon

Stereoisomers

2 different amino acid forms L R handedness

L vs. D amino acids

Left vs Right

Peptide bonds

How amino acids are linked together to form proteins

Side chain

Structure on the amino acid that determines the identity/properties of the amino acid

Nonpolar/hydrophobic amino acids

Glycine (Gly), Alanine (Ala), Valine (Val), Leucine (Leu), Isoleucine (lie), Methionine (Met), Proline (Pro), Phenylalanine (pue), Tryptophan (Trp)

Polar, uncharged amino acids

Serine (S), Threonine (Tur), Asparagine (Asn), Glutamine (Gln), Tyrosine (Tyr)

Basic amino acids

Lysine (Lys), Arginine (Arg), Histidine (His)

Acidic amino acids

Aspartic Acid (Asp), Glutamic Acid (Glu)

Aliphatic

It has no aromatic ring

Diprotic

Amino acids are diprotic, has 2 pKa's in 2 buffer regions at different pH levels

Isoelectric point (pI)

pH when net charge is 0

pI of Leu

6

pI of Met

5

Peptide bond

Covalent bond between the a-carboxly group and α-amino group of different amino acids

What is lost when a peptide bond forms?

H2O

Peptides vs polypeptide chain

peptides are links of serval amino acids and polypeptide chains are links of >100 amino acids, making proteins

N-terminal vs C terminal

1st amino acid vs Last amino acid

Function in proteins

Determined by Structure: SEQUENCE -> STRUCTURE -> FUNCTION

Effect of mutation from Glu to Val

Affects primary structure

Why is sickle cell more common near the equator?

Mutation against malaria

Psi vs Phi bond

C-C vs C-N

Bond stabilizing the turn of the alpha Helix

H bond

Primary structure of a protein

Determines the 3D structure of the protein