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Eiji Fujimori and Kenneth Quinlan 



fluorescence shows two distinct bands at about 590 and 620 m|j. (Fig, 4) 

 which correspond to at least two different types of chromophores. These 

 results are in agreement with the observation of Berns, et al. ^'> on phy- 

 cocyanin obtained from the blue-green alga, Plectonema calothricoides. 

 The existence of two chromophores has further been verified by the reduc- 

 tion of the 590 m|j. chromophore with sodium hydrosulfite. The shift of the 

 fluorescence band towards longer wave-length when excited by light 

 longer than 615 m|jL shows that both chromophores are capable of fluores- 

 cing. Their fluorescence peaks have been estimated to be at 630 and 

 650 mjji. 



In the presence of PC MB the absorption and fluorescence of phycocyanin 

 decreases. This decrease can be partially recovered by the addition of 

 glutathione as shown in the action spectra in Fig. 4. The same effect has 

 been found in phycoerythrin. The change of the spectral properties of 

 phycocyanin on the addition of PCMB is less than that of phycoerythrin. 

 This is in good agreement with the result showing a much smaller sulfhy- 

 dryl content for the phycocyanin. Amperometric titrations show a 

 sulfhydryl content of one per molecule of phycocyanin. The molecular 

 weight and specific extinction coefficient used were 273,000 (^ and 

 7.9 at 615 mpi ^ ', respectively. The action spectrum of the shorter wave- 

 length fluorescence suggests that PCMB does not influence this radiative 

 transition (Fig. 4). The sulfhydryl blocking agent influences only the 

 longest wave-length chromophore as found with phycoerythrin. These 

 chromophores may in some way be bonded to the protein through the sul- 

 fhydryl group. 



RED AND BLUE-GREEN ALGAE 



The present study has shown that the longest wave-length chromophore 

 of the purified phycobilins is associated with sulfhydryl groups since 

 PCMB inactivates the longest wave-length absorption. This particular 

 chromophore is also capable of receiving energy from the shorter wave- 

 length chromophores. This investigation was extended to observe the 

 effect of PCMB on the spectral behavior of phycobilins and chlorophylls in 

 the whole and ruptured cells of red and blue-green algae. These results 

 may give additional information on the role of accessory pigments and 



