Exploring
the Conformational Space of Cysteine by
Matrix Isolation Spectroscopy Combined with Near-Infrared Laser Induced
Conformational Change
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Abstract
Six conformers of α-cysteine
were identified by matrix isolation
IR spectroscopy combined with NIR laser irradiation. Five of these
conformers are identical with the five out of six conformers that
have recently been identified by microwave spectroscopy. The sixth
conformer observed in the present study is a short-lived conformer,
which decays by H-atom tunneling; its half-life in a 12 K N<sub>2</sub> matrix is (1.1 ± 0.5) × 10<sup>3</sup> s. This study proves
that matrix isolation IR spectroscopy combined with NIR laser irradiation
is a suitable method to identify conformers of a complex system for
which computations predict several dozens of conformers, and that
the reliability of this method for conformational assignment is comparable
to that of microwave spectroscopy