CRYSTALLIZATION AND PRELIMINARY-X-RAY DIFFRACTION STUDIES OF C-PHYCOCYANIN FROM A RED ALGA, PORPHYRA-TENERA

C-Phycocyanin from a red alga, Porphyra tenera, has been crystallized by the vapor-diffusion procedure. Both orthorhombic and hexagonal forms were obtained from ammonium sulfate solutions, whereas only the orthorhombic form was selectively grown from sodium citrate solutions. The orthorhombic crystals are more suitable for further crystallographic work; their space group is P212121, with unit-cell dimensions of a=105, b=121, and c=184 A. The asymmetric unit comprises two (αβ)3 trimer molecules of C-phyco-cyanin. These crystals diffract X-rays up to about 3 A resolution. © 1990 Copyright, 1990 by the Journal of Biochemistry.