4-Oxoproline as a Site-Specific Infrared Probe: Application To Assess Proline Isomerization and Dimer Formation
Rachel M Abaskharon1, Debopreeti Mukherjee1, Feng Gai1
1Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States.
Abstract:
Due to its unique structure, proline plays important structural and functional roles in proteins. However, this special amino acid lacks an adequate vibrational mode that can be exploited to probe its local electrostatic and hydration status via infrared spectroscopy. Herein, we show that the C═O stretching vibration of a proline derivative, 4-oxoproline, is sensitive to local environment and hence can be used as a site-specific infrared probe. We further validate this notion by applying this unnatural amino acid to assess the thermodynamics of proline cis-trans isomerization in a peptide environment and examine the amino acid dimer formation in concentrated proline and glycine solutions.
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