ISSN:
1432-072X
Keywords:
Biliproteins
;
Phycoerythrocyanin
;
c-Phycocyanin
;
Allophycocyanin
;
Anabaena azollae
;
Azolla caroliniana
;
Photosynthesis and nitrogen fixation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The endophytic cyanobacterium, Anabaena azollae, isolated from laboratory cultures of Azolla caroliniana Willd., contains three spectroscopically distinct biliproteins. About 70% of the biliprotein is c-phycocyanin (λmax 610 nm) and 13% is allophycocyanin (λmax 647 nm, shoulder 620 nm). A third pigment corresponds to phycoerythrocyanin (λmax 570 nm, shoulder 590 nm). In very dilute solutions of allophycocyanin, at constant pH and buffer strength, the 647 nm maximum disappears and a single λmax occurs at 615–620 nm. The 647 nm absorption maximum reappears upon concentrating the dilute solution. Very dilute solutions of phycoerythrocyanin exhibit a broad peak between 570 and 590 nm. Absorption spectra of c-phycocyanin are not significantly altered upon dilution. Fluorescence emission maxima of phycoerythrocyanin, c-phycocyanin, and allophycocyanin occur at 630 nm, 643 nm and 660 nm respectively, using 540 nm excitation. Two subunits, of molecular weight 16,500 (α) and 20,600 (β), are seen in c-phycocyanin upon dissociation with SDS. Dissociation of allophycocyanin and phycoerythrocyanin with SDS yields one sizeclass of subunits, with a molecular weight of about 17,500 for allophycocyanin and 18,000 for phycoerythrocyanin.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00422303
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