Why only L-amino acids in proteins? скачать в хорошем качестве

Why only L-amino acids in proteins?

Chiral biasness has been an integral part of biology. Proteins are made up of only L-amino acid isomers. The importance of chiral specificity in biology can be seen in the case of Thalidomide. Video Link of the video on Thalidomide:    • Worst Medical Disaster-Thalidomide   In this video we discuss theories related to the selection of L-amino acids over D-amino acids for their olymerization as peptides. A basic understanding about chirality would make the topic easier to understand. Of the many theories we have disscussed a few major and well known theories: Parity violating energy difference (PVED) which proposes existence of energy difference between the two isomers which leads to selection of L-isomers. Differential adsorption of isomers on calcite crystals has been proposed to play a role. As the hot prebiotic soup started cooling, this resulted in the crystallization and precipitation of excess D-amino acid isomers leaving behind abundant L-amino acid isomers for polymerization. Sunlight has been proposed to circularly polarized in a particular orientation which degrades D-amino acid isomers and hence leaves L-amino acids for peptide formation. Certain experimental evidences have shown the role of RNA in the chiral bias of proteins. Also the role of autocatalysis on the abundance of L-amino acids in proteins has been disscussed. Please Subscribe to Biogyan. Please Like and Share the video. Thank you.