Isomerism and Chirality

Isomers:

different molecules but same atomic composition

Stereo-isomers:

molecules with same groups and bonding, but different spatial organisation

Chirality

is due to stereo-isomers ; this is the ‘handedness of molecules’

just look at this 

•Chiral molecules have the same MOLECULAR formula

They have  left- and right-handed isomers called enantiomers

•All the amino acids used to make your proteins are L-isomers

•Enzymes and receptors will  recognise a specific enantiomer of a chiral molecule

•GluR respond to L-glutamate but not D-glutamate

Thalidomide is a chiral molecule: has (R)- and (S)- enantiomers

•(R)-enantiomer acts as a sedative and was used to treat morning sickness.

•(S)-enantiomer acts as a teratogen causing birth defects. It is estimated that worldwide 10000 infants were born with limb malformation and other problems.

•The enantiomers can inter-convert in vivo.

•This tragedy led to more stringent drug testing and approval regulations.