Common Motif at the Red Luminophore in Bovine Serum Albumin–, Ovalbumin–, Trypsin–, and Insulin–Gold Complexes

• Published in: The journal of physical chemistry letters Vol. 12; no. 11; pp. 2865 - 2870
• Main Authors: Dixon, Jacob M, Egusa, Shunji
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 25.03.2021
• Subjects: Physical Insights into Materials and Molecular Properties
• ISSN: 1948-7185; 1948-7185
• DOI: 10.1021/acs.jpclett.1c00222

We examined the static and dynamic characters of the red luminescence in the protein–Au­(III) compounds, directly comparing multiple proteins: BSA, OVA, trypsin, and insulin. These four protein–Au­(III) complexes showed a nearly identical excitation–emission pattern, not only the wavelength of luminescence (λem ∼ 640 nm). Lifetimes of the red luminescence shared a common value of ∼300 ns. Kinetics of the luminophore formation was consistently described by a Langmuir-type chemisorption of Au­(III) for these proteins, coinciding with the protein conformation change at pH ∼ 10. These observations and the protein structural analyses support that the red luminophore formation involves Au­(III) coordination to a common motif within these proteins.