Amino acids and peptides

This is a condensation reaction. Short version of the mechanism. Amino group of the green amino-acid attacks the carboxilic acid group of the purple amino acid. The water is released in the process. Note that the reaction in the opposite direction called hydrolysis.

In reality this reaction is not possible, in biological systems it is catalyzed during traslation by ribosomes trough an alternative mechanism.

1. CORN steriochemistry.

2. Zwitterions.

A zwitterion is a molecule with two or more functional groups, of which at least one has a positive and one has a negative electrical charge, so the net charge of the entire molecule is zero.

3. Isoelectric point.

Is the pH at which all of the molecules are in zwitterionic form and carry no net electrical charge.

4. Dihedral Angles.

Dihedral angle - is the angle between two intersecting planes. In biochemistry dihedral angles are used to describe the folding of peptides and proteins.

φ - is used to describe the angle between 2 carbonyls.
ψ - is used to describe the angle between 2 amides.
ω - is the same as peptide bond, this angle is fixed due to resonance and is equal to 180 degree.