Protein Crystallography project

This is a Protein Crystallography Project concerned with the Determination of Protein Structures in Crystals and in Solutions with electrolytes by X-ray Diffraction, neutron diffraction, light scattering, Vibrational Circular Dichroism (VCD) and 2D-NMR.

Lecture Notes on Paracrystal Theory and Quasi-crystals

 * The following figures and data have the following Source: An Introduction to Molecular Biology/Function and structure of Proteins



Amino Acid Structures and Properties
The 20 amino acids encoded directly by the genetic code can be divided into several groups based on their properties. Important factors are charge, hydrophilicity or hydrophobicity, size and functional groups.Amino acids are usually classified by the properties of their side chain into four groups. The side chain can make an amino acid a weak acid or a weak base, and a hydrophile if the side chain is polar or a hydrophobe if it is nonpolar.

Protein amino acids are combined into a single polypeptide chain in a condensation reaction. This reaction is catalysed by the ribosome in a process known as translation.

Polar and non polar amino acids and their single and three letter code

Additionally, there are two additional amino acids which are incorporated by overriding stop codons:

In addition to the specific amino acid codes, placeholders are used in cases where chemical or crystallographic analysis of a peptide or protein can not conclusively determine the identity of a residue.

Amino Acid Structure Gallery
The 20 naturally occurring amino acids have different physical and chemical properties, including their electrostatic charge, pKa, hydrophobicity, size and specific functional groups. These properties play a major role in molding protein structure. The salient features of amino acids are described below in the table.