Different Structural Behaviors Evidenced in Thaumatin-Like Proteins: A Spectroscopic Study

• Published in: The Protein Journal Vol. 27; no. 1; pp. 13 - 20
• Main Authors: Perri, F., Romitelli, F., Rufini, F., Secundo, F., Di Stasio, E., Giardina, B., Vitali, A.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 2008; Springer Nature B.V
• Subjects: Animal Anatomy; Antifungal Agents - chemistry; Biochemistry; Bioorganic Chemistry; Cassia; Cassia - chemistry; Chemistry; Chemistry and Materials Science; Circular Dichroism; Histology; Morphology; Organic Chemistry; Plant Proteins - chemistry; Protein Folding; Proteins; Rigidity; Spectrometry, Fluorescence; Spectroscopy, Fourier Transform Infrared; Studies; Unfolding; Intrinsic fluorescence; Thaumatin-like protein; Circular dichroism
• ISSN: 1572-3887; 1573-4943; 1875-8355
• DOI: 10.1007/s10930-007-9103-2

Three proteins belonging to the thaumatin-like proteins family were compared in this study from a structural point of view: zeamatin, a new recently isolated PR-5 from Cassia didymobotrya and the commercial sweet-thaumatin. The former two proteins possess antifungal activities while commercial thaumatin is well known to be a natural sweetener. Intrinsic fluorescence studies have evidenced that the three proteins behave differently in unfolding experiments showing different structural rigidity. All the three proteins are more stable at slight acidic buffers, but sweet-thaumatin has a major tendency to destructurate itself. Similar observations were made from circular dichroism studies where a structural dependence relationship from the pH and the solvent used confirmed a hierarchic scale of stability for the three proteins. These structural differences should be considered to be significant for a functional role.