A time-dependent density functional theory investigation of the spectroscopic properties of the beta-subunit in C-phycocyanin.
By using time-dependent density functional theory combined with the polarizable continuum model, a satisfactory assignment of the absorption and circular dichroism spectra and energy transfer flow of the beta-subunit in C-phycocyanin (C-PC) was achieved when the protonation of beta-84 and beta-155 phycocyanobilin (PCB) and their interaction with the protein moiety in C-PC have been taken into account. We attribute the main peak for both beta-84 and beta-155 as arising from the pi electron excitation of the pyrrole rings and the shoulder peak as arising from the charge transfer from the asparate residue to PCBH(+). The satisfactory agreement between theory and experiment suggests that Förster resonance theory prevails such that energy transfer occurs from beta(s) (beta-155) to beta(f) (beta-84).
Ren
Yanliang
Y
Key Laboratory of Pesticide & Chemical Biology (CCNU), Ministry of Education, Department of Chemistry, Central China Normal University, Wuhan 430079, China.
Wan
Jian
J
Xu
Xin
X
Zhang
Qingye
Q
Yang
Guangfu
G
D000042:Absorption; D001224:Aspartic Acid / Q000737:chemistry; D002942:Circular Dichroism; D000458:Cyanobacteria / Q000378:metabolism; D008956:Models, Chemical; D008958:Models, Molecular; D008962:Models, Theoretical; D008968:Molecular Conformation; D052980:Phycobilins / Q000737:chemistry*; D010798:Phycocyanin / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D012984:Software; D013053:Spectrophotometry / Q000379:methods*; D013997:Time Factors
D052980:Phycobilins; D010798:Phycocyanin; D001224:Aspartic Acid; C011069:phycocyanobilin