Spectral analyses during the isolation course of Spirulina platensis phycobilisomes using low-speed centrifugation

The phycobilisomes were isolated from Spirulina platensis using low-speed centrifugation. The crude phycobilisomes solution extracted by Triton X-100 was centrifugated (13 000 rpm) four times. The centrifugated phycobilisomes solution was spectrally analyzed using absorption spectrum each time. The absorption spectrum showed that the ultraviolet absorption maximum of the phycobilisomes solution was still at 263 nm, and also exhibited the characteristic chlorophyllous absorption in the rang of 400-450 nm. after the fourth centrifugation. This indicated that there existed small quantities of Triton X-100 and chlorophyll in the centrifugated phycobilisomes solution. But the ultraviolet absorption maximum was red-shifted to 277 nm and the chlorophyllous absorption was not observed in the absorption spectrum of the phycobilisomes solution obtained by high concentration salt precipitation, which meant that the method of high concentration salt precipitation could effectively remove Triton X-100 and chlorophyll from the phycobilisomes solution. The precipitated phycobilisomes of Spirulina platensis were further purified by using Sepharose CL-6B column chromatography. The fluorescence emission maximum of the purified phycobilisomes at room temperature was at 680 nm, which indicated that the purified phycobilisomes were intact.