Interfacial Properties Of The Fluorescent Protein B-phycoerythrin Extracted From The Red Microalga Rhodosorus Marinus

Abstract

Fluorescent proteins have been used as biomarkers long time ago. In this work we show the extraction, spectroscopic characterization and some interfacial properties of B-Phycoerythrin obtained from the red microalga Rhodosorus marinus. Rhodosorus marinus showed three types of phycobiliproteins: Phycoerythrin, phycocyanin and allophycocyanin. However the highest proportion was for B-Phycoerythrin. It is widely used as a fluorescent probe, analytical reagent, natural dye in foods and cosmetics, in the development of biosensors and also has been shown to have a therapeutic value due to their inmunomodulating and anti-carcinogenic activities The spectroscopic characterization was performed by UV, fluoresence and cicrular dichroism. The purified B-phycoerythrin showed a A(545)/A(495) ratio of 4.8, peaks at 540, 562 nm with a 498 shoulder, a fluorescence emission a maximum at 578 nm, and a secondary structure almost stable with pH changes The surface properties of B Phycoerythrin were analised with a Langmuir Balance. Diferent pH conditions in the subphase were used. The protein monolayers were very stable with an acidic subphase. Brewster angle microscopy was used to visualise the protein domins at the air-water interface. AFM images were obtained for diferent pH conditions in the subphase. Very stable and ordered Langmuir-Blodgett protein monolayers were measured.