besides being the building blocks of peptides and proteins,
are of special interest to structural chemistry. The reason of
this special interest is the fact that amino acids form zwitterions
HN-X-COO in the solid state and in polar media, but
neutral molecules HN-X-COOH in the gas phase or in matrix isolation.
( Zwitterion to neutral conversion, animation for
Amino acids form very stable crystals that, under
atmospheric pressure, in most cases decompose before melting.
Experimental studies of the neutral form therefore
require sophisticated techniques.
Quantum chemical calculations, in contrast, deal with isolated molecules
in vacuo and require additional concepts to treat any
effects of the molecular environment. Quantum chemical calculations
are therefore an ideal tool for the study of neutral amino acids.
The following pages give selected results of an ab initio
study of -amino
acids (glycine, -alanine,-aminobutyric
Each page is devoted to a single amino acid and contains several
illustrative pictures of relevant conformers.
Although most of the information is contained in the text, so that
a text-only browser is basically sufficient, these
pictures will help in understanding. Therefore, if your
browser can load pictures, you might want to turn that option on.
The bottom of each page provides links for
forward and backward browsing and, in the center entry,
an interface to the literature data base of the Institute of
Physical and Theoretical Chemistry. Activation of this interface
produces an up-to-date list of publications and theses that
relate to the specific compound.