Hyderabad: In a finding that would help understand evolution of life and also have implications for medical science, scientists today said they have been able to solve the mystery of nature in protein synthesis.
The research explaining the breakthrough by scientists at the CSIR-Centre for Cellular and Molecular Biology (CCMB), titled `Mechanism of chiral proofreading during translation of genetic code`, was published in the journal `eLIFE` today.
The finding revealed the mechanism by which D-amino acids are removed from protein synthesis. "We have now, with the help of Structural Biology tools, been able to solve this nature`s mystery and show the precise mechanism by which only L-amino acids are allowed to form proteins while D-amino acids are removed by an enzyme called DTD.
"The study has significantly advanced our knowledge on a very fundamental aspect of life and explains why we do not have a mirror image biological world," CCMB Director Mohan Rao told reporters here, accompanied by senior scientist Sankaranarayanan.
"Most of the biological processes occurring in a living cell, from the simplest of bacteria all the way to humans, are carried out by proteins.
"These are long polymers made out of very basic building blocks known as amino acids linked together like a chain of beads, as dictated by the genetic code.
"This chain then folds to form specialised molecular machines that carry out specific cellular tasks like metabolic reactions, regulation of genes etc. Therefore, life depends heavily on the way the amino acids are assembled to form proteins," Rao explained. Amino acids are `chiral` (asymmetric in such a way that the structure and its mirror image are not superimposable)?molecules, which means that there are two possible forms of it, he said.
"In simple terms, what we see as the biological world today, starting from the simple single-cellular organisms to complex ones like humans, represents only one of the two mirror images," he said.
"In order to maintain this homochirality, all organisms employ an active mechanism that prevents D-amino acids (mirror image of L-amino acids) from entering the protein synthesising factory (ribosomes) of the cell."