|
Biosensors are finding numerous applications in clinical diagnosis, drug discovery, biotechnology, environmental
monitoring and etc. Hemoglobin (Hb), a natural heme containing protein, exhibits enzymatic activity towards hydrogen
peroxide, which is possible to improve by altering the heme orientation and/or changing the microenvironment in the
vicinity of the heme sites. It was shown that hypericin (HY), a naphthodianthrone from Hipericum perforatum and a
potent photosensitizer, interacts with Hb and causes conformational changes of the protein. These results were gained
both in dark and under visible light exposure by absorption and fluorescence spectroscopy. It was shown that
photodynamic influence of HY leads to Hb absorption decrease at Soret band, depending on HY concentration and
irradiation doze. Excitation of Hb/HY complexes leads to reduction of some emission peaks, correlating with the
concentration of HY, incubation and irradiation time. The incubation and irradiation of complexes leads to an increase in
electrophoretic mobility of Hb and its peroxidase activity. Under the HY influence Hb properties as a hydrogen peroxide
detector could be improved and an effective determination of peroxide formation could be achieved. This makes Hb an
attractive 'recognition' element for construction of third-generation biosensors.
|
