Essay on Chirality, Enantimomers and Their Significance

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One of the great conundrums in biochemistry is the homochirality of life’s building blocks. Natural sugars exhibit a nearly exclusive right-handedness; DNA demonstrates a supramolecular left-handed chirality, while amino acids exhibit an exclusive left-handedness. Chiral molecules have an asymmetric central atom, surrounded by four different functional groups. This three-dimensional structure makes enantimomers, which are not super imposable mirror images of one another (Figure 1a). These molecules are optically active – that is they rotate the plane of polarized light in opposite directions of one another.
Non-biological or prebiotic methods of amino acid synthesis produce racemic mixtures (about equivalent concentrations L and D
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Finally, polymerization of these amino acids, had to favor a uniform chirality from the beginning, before specific substrates had formed or were needed. This paper will focus on the discussion of the first two steps in this process.

Prebiotic Synthesis of Amino Acids Amino acid synthesis is the first step we must look at to consider the reason for homochirality. The first and most well-known of potential terrestrial origins of amino acids comes from Miller and Urey (1953). The experiment synthesized numerous amino acids by applying electric disharges to a mixture CH4, NH3, H2O and H2 – believed at the time to be atmospheric conditions of earth at the time.
Whether organic synthesis of amino acid is terrestrial or extraterrestrial, and the mechanism of synthesis is a topic that remains heavily debated. In part this is due to our limited knowledge about prebiotic conditions on Earth and potential precursors for amino acid synthesis.
Miller-Urey provided evidence that prebiotic conditions could have produced a small number of biochemically significant compounds such as amino acids, hydroxy acids and urea and not a random mixture of organic molecules. As our understanding of the primordial conditions has improved, the essence of the Miller-Urey experiment has withstood the test of time. An in-depth review of pre-biotic synthesis conditions is beyond the scope of this paper but see Bada

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