<unk>  can exist in either of two enantiomeric forms, L-glutamine and D-glutamine. The L-form is found in nature.<unk>  contains an α-amino group which is in the protonated −NH3+ form under biological conditions and a carboxylic acid group which is in the deprotonated −COO− form, known as carboxylate, under physiological conditions.<unk>  zwitterionic forms at neutral pH: L-glutamine (left) and D-glutamine
Glutamine
Inositol
Choline
Gluten
Nicotinamide
Cysteamine
Glutamate 
Phenserine