Question

ginv the long answer with diagram protein structure and ramachandran polt​

Answer 1

Answer:

A Ramachandran plot is a way to visualize backbone dihedral angles ψ against φ of amino acid residues in protein structure. A Ramachandran plot can be used in two somewhat different ways. One is to show in theory which values, or conformations, of the ψ and φ angles are possible for an amino-acid residue in a protein. A second is to show the empirical distribution of datapoints observed in a single structure

The colouring/shading on the plot represents the different regions described in Morris et al. (1992): the darkest areas correspond to the "core" regions representing the most favorable combinations of phi-psi values.

Ideally, one would hope to have over 90% of the residues in these "core" regions. The percentage of residues in the "core" regions is one of the better guides to stereochemical quality. The different regions were taken from the observed phi-psi distribution for 121,870 residues from 463 known X-ray protein structures. The two most favoured regions are the "core" and "allowed" regions which correspond to 10° x 10° pixels having more than 100 and 8 residues in them, respectively. The "generous" regions were defined by Morris et al. (1992) by extending out by 20° (two pixels) all round the "allowed" regions. In fact, the authors found very few residues in these "generous" regions, so they can probably be treated much like the "disallowed" region and any residues in them investigated more closely.