title: Kinetics of allophycocyanin's trimer-monomer equilibrium.
abstract: Kinetic studies of the dissociation of allophycocyanin trimers to monomers have been performed by using stopped-flow techniques. The dissociation was monitored by two techniques: by light scattering to observe the molecular weight changes directly and by 650-nm absorbance to observe the linkage of quaternary structure to spectra. The light-scattering experiments showed a simple exponential decay of trimers to monomers with a dissociation constant of 0.23 s-1. The absorption changes were complex, with two processes occurring. The faster absorption change appeared to be almost simultaneous with the molecular weight change (about 0.27 s-1) and was perhaps totally coordinated with it. The slower absorption change (0.071 s-1) was possibly a result of a conformational change in the chromophore arising during the conversion from newly dissociated monomers to equilibrium monomers.
mesh_terms: D000458:Cyanobacteria / Q000378:metabolism; D007700:Kinetics; D008027:Light; D046911:Macromolecular Substances; D010798:Phycocyanin / Q000378:metabolism*; D010860:Pigments, Biological / Q000378:metabolism*; D012542:Scattering, Radiation; D013053:Spectrophotometry
chemical_list: D046911:Macromolecular Substances; D010860:Pigments, Biological; C002497:allophycocyanin; D010798:Phycocyanin