View source for D isomer

&nbsp;The D isomer is one of two forms of optical isomer, arising from the prescence of a [[Chiral carbon|chiral carbon]]. 'D' stands for dextrorotary, meaning that the isomer rotates plane polarised light clockwise.<ref>http://www.elmhurst.edu/~chm/vchembook/209optical.html</ref>&nbsp;<br><br>In natural [[Sugar|sugars]], the D isomer occurs more commonly than the&nbsp;[[L isomer|L is]]<span style="line-height: 1.5em;">[[L isomer|omer]], although it is not clear why, and often the two isomers can have widely diffferent effects.</span><ref>https://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb1/part2/sugar.htm</ref> 

A well known example of the difference between D and L isomers is that of [[Thalidomide|Thalidomide]], which was in the past given to pregnant women to counter the effects of [[morning sickness|morning sickness]]. The drug was given as a [[Racemic_mixture|racemic mixture]], and while the D isomer was effective at curing morning sickness, the L isomer caused severe limb abnormalities in the developing [[foetus|foetus]]. Thousands of children were born with abnormal or underdeveloped limbs, and thalidomide was banned in many countries. Since the thalidomide disaster, all chiral molecules are rigorously tested before being marketted to the public, and racemic mixtures are very rarely sold.<br><br> 

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