Artificial chaperone-assisted renaturation of R-PE subunits

Abstract

The isolated α, β and two γ subunits of the R-phycoerythrin (R-PE) from Polysiphonia urceolata were renaturated by the artificial chaperone technique in combination with β-cyclodextrins. The molecular weights determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) are 17 580, 19 050, 32 500 and 34 060 for the α, β, γ₁ and γ₂ subunits, respectively. The renaturation yields of the four subunits obtained by the artificial chaperone technique are several times higher than those achieved by conventional methods. The two γ subunits are suggested to be naturally present species, instead of artificial products, considering the molecular weights and spectral features. The existence of two kinds of γ subunits may explain the failure to determine the entire structures of R-PE, b- or B-phycoerythrin (b- or B-PE) by X-ray crystal structural analyses.