The synchronous fluorescence (SF) technique can provide some useful information with the endogenous fluorophores in complex systems. The SF technique has been used in the characterization of the type I collagen in PBS solution (pH=7.4) and the photo-reaction of hypocrellin B (HB) with type I collagen in solution irradiation with the 475 nm light under saturated by oxygen, air and nitrogen respectively. The SF spectra show the peaks attribute to tyrosine residues (275 nm) and pyridinoline cross-link (325 nm) in collagen. The photo-induced reaction with HB causing the fluorescence quenching but no wavelength shift, this suggests the photo-reaction don’t changing the microenvironment of PYD cross-link. The fluorescence quenching rate is faster than others when the solution saturated by oxygen. The results imply that the photo-induced reaction is oxygen dependence.
In the current work, Hypocrellin A (HA) is one of the nature photosensitizer was recognized by researchers, and it used
as a probe to research the molecular recognition and interaction with protein, the work suggested the HA can as the
medicine to treat some disease. This paper study the spectrum character of photoreaction of Hypocrellin A and cysteine
in different pH value, the spectrum show an isosbestic point at 495nm, and the absorption peak at 478nm was red-shifted
to about 500nm. The result suggested the HA can react with cysteine in this condition, and farther illuminated the
cysteine residue may is one of the target of the interaction of HA or HB with protein.