CORN law

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The CORN law is the rule that allows to distinquish enantiomers from each other. In other words, it determines whether the amino acid is a L-isomer or D-isomer. All amino acids have the same core and differ due to their side chain. There are four different groups attached to α-carbon, making α-amino acids chiral. These groups are: carboxylic acid group (-COO-), amino group (-NH2), a hydrogen atom and a distinctive R group (representation of side chain).

The CORN is an acronym for -COOH , the -R and -NH2 groups. If the carboxyl group is followed by the R group and the amino group in a clockwise direction, then the amino acid is an L-isomer. If the movement is in the anticlockwise direction, the amino acid is a D-isomer[1].


  1. Jeremy M. Berg, John L. Tymoczko, Lubert Stryer. Biochemistry. 7th. ed. New York: WH Freeman and Company. 2011.
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