G. N. Ramachandran

G. N. Ramachandran (1922–2001) was an Indian biophysicist who developed the Ramachandran plot to map sterically allowed protein-backbone conformations.

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C. V. Raman: An Indian physicist who won the 1930 Nobel Prize in Physics for discovering the Raman effect. Ramachandran trained in physics in India during the scientific era Raman had helped establish.
Ramachandran plot: A graph of backbone dihedral angles that identifies sterically allowed conformations in proteins. This is Ramachandran's best-known tool, mapping the conformational space his analysis predicted.
Protein: A chain or assembly of amino acids that folds into a specific structure and performs biological functions. Ramachandran's geometric constraints apply to the backbone of these macromolecules.
Protein structure validation: The assessment of whether a proposed protein structure is consistent with physical and experimental constraints. Backbone-angle outliers flagged by the plot can reveal errors in structural models.
Viswanathan Sasisekharan: An Indian biophysicist who collaborated with Ramachandran on protein structure and conformational analysis. Their joint work developed the steric analysis behind the conformational map.
Linus Pauling: An American chemist whose work explained chemical bonding and helped establish principles of protein structure. Pauling's structural models formed part of the scientific context for Ramachandran's protein studies.
Steric hindrance: Repulsion caused when atoms are forced too close together in space. Overlapping atomic volumes exclude much of the backbone-angle space in the plot.
Amino acid: An organic molecule with amino and carboxyl groups; amino acids are the monomers of proteins. Each residue contributes the backbone atoms whose steric interactions constrain its conformation.
Protein folding: The process by which a protein chain adopts a functional three-dimensional structure. Allowed backbone conformations constrain the shapes available during folding.
Collagen: A structural protein whose distinctive triple-helical arrangement is abundant in connective tissues. Research on collagen structure helped motivate Ramachandran's broader investigation of protein geometry.