R-PHYCOERYTHRIN FROM Porphyra yezoensis UEDA AND ITS PRELIMINARY CRYSTALLOGRAPHY STUDY

Native R-phycoerythrin from Porphyra yezoensis has a molecular weight of 230, 000±23,000 dalton in 0.05 mol/L potassium phosphate at pH 7.5 and an absorption spectrum with the maxima at 565 and 498 nm and a shoulder at 540 nm, Its fluorescence emission maximum is at 578 nm in the above buffer. Single crystal X-ray diffraction investigation is in progress from R-phycoerythrin. It is crystallized in the rhombohedral space group R_3 with a=b=187.5±2.5, c=60.0±3,0. The densities measured on the crystals and its mother liquor are 1.215 g/cm~3 and 1.070 g/cm~3 respectively. The fraction of the crystal volume occupied by the protein is 51.5%.It has been estimated that the ctystallographic asymmetric unit in rhombohedral lattice might contain (αβ)_2 with a total molecular mass of less than 8×10~4 dalton. The hexagonal unit cell could accommodate three cylindrical molecules 108 in diameter and 60 in height, which is dictated by the space group symmetry for packing into the unit cell.

R-PHYCOERYTHRIN FROM Porphyra yezoensis UEDA AND ITS PRELIMINARY CRYSTALLOGRAPHY STUDY