Open AccessX‐ray crystallographic studies on C‐phycocyanins from cyanobacteria from different habitats: marine and freshwater
Author(s) -
Satyanarayana L.,
Suresh C. G.,
Patel Anamika,
Ghosh Pushpito Kumar,
Mishra Sandhya
Publication year - 2005
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
ISSN - 1744-3091
DOI - 10.1107/s1744309105025649
Subject(s) - lyngbya , monoclinic crystal system , crystallography , crystal (programming language) , phycocyanin , cyanobacteria , hexagonal crystal system , crystal structure , chemistry , biology , bacteria , genetics , computer science , programming language
C‐phycocyanins from three cyanobacterial cultures of freshwater and marine habitat, Spirulina , Phormidium and Lyngbya spp., were purified to homogeneity and crystallized using the hanging‐drop vapour‐diffusion method. Blue‐coloured crystals in different crystal forms, monoclinic and hexagonal, were obtained for the three species. The crystals took 1–12 weeks to grow to full size using polyethylene glycols of different molecular weights as precipitants. The amino‐acid sequences of these proteins show high similarity to other known C‐phycocyanins from related organisms; however, the C‐phycocyanins reported here showed different biochemical and biophysical properties, i.e. molecular weight, stability etc . The X‐ray diffraction data were collected at resolutions of 3.0 Å for the monoclinic and 3.2 and 3.6 Å for the hexagonal forms. The unit‐cell parameters corresponding to the monoclinic space group P 2 1 are a = 107.33, b = 115.64, c = 183.26 Å, β = 90.03° for Spirulina sp. C‐phycocyanin and are similar for crystals of Phormidium and Lyngbya spp. C‐phycocyanins. Crystals belonging to the hexagonal space group P 6 3 , with unit‐cell parameters a = b = 154.97, c = 40.35 Å and a = b = 151.96, c = 39.06 Å, were also obtained for the C‐phycocyanins from Spirulina and Lyngbya spp., respectively. The estimated solvent content is around 50% for the monoclinic crystals of all three species assuming the presence of two hexamers per asymmetric unit. The solvent content is 66.5 and 64.1% for the hexagonal crystals of C‐phycocyanin from Spirulina and Lyngbya spp. assuming the presence of one αβ monomer per asymmetric unit.