title: Physico-chemical factors affecting the in vitro stability of phycobiliproteins from Phormidium rubidum A09DM.
abstract: The functionality and stability of phycobiliproteins (PBPs) phycoerythrin (PE), phycocyanin (PC) and allophycocyanin (APC) were investigated under various temperatures, pHs and oxidative stressors. All PBPs were thermostable up to 4-40°C; however, their concentration decreased rapidly at 60-80°C. The maximum stability of all PBPs was in the pH range 6.0-7.0. Decrease in PBPs content was found under high acidic (pH 2-4) and alkaline conditions (pH 8-12). The oxidizing agent (0.1-0.6%) showed the least effect on the stability of PBPs; however, 0.8-1.0% H2O2 caused significant loss of PBPs. Contrary to PE, PC and APC was more susceptible to an oxidizing agent. The chromophore associated with α- and β-subunit of PBPs and thus, their functionality (fluorescence) was severely affected under high temperature (60-80°C), and oxidizing agent, as well as low (2-4) and high (8-12) pH. Contrary to PC and APC, functionality of PE was surprisingly maintained even at pHs 6-12 and under oxidative stress.
authors.affiliation: BRD School of Biosciences, Vadtal Road, Satellite Campus, Post Box No. 39, Sardar Patel University, Vallabh Vidyanagar 388 120, Anand, Gujarat, India. Electronic address: raj_rastogi@rediffmail.com.
authors.forename: Rajesh Prasad
authors.initials: RP
authors.lastname: Rastogi
authors.affiliation: BRD School of Biosciences, Vadtal Road, Satellite Campus, Post Box No. 39, Sardar Patel University, Vallabh Vidyanagar 388 120, Anand, Gujarat, India. Electronic address: ravi123sonani@gmail.com.
authors.forename: Ravi Raghav
authors.initials: RR
authors.lastname: Sonani
authors.affiliation: BRD School of Biosciences, Vadtal Road, Satellite Campus, Post Box No. 39, Sardar Patel University, Vallabh Vidyanagar 388 120, Anand, Gujarat, India. Electronic address: datta_madamwar@yahoo.com.
authors.forename: Datta
authors.initials: D
authors.lastname: Madamwar
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis / Q000737:chemistry*; D000458:Cyanobacteria / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D052979:Phycobiliproteins / Q000032:analysis / Q000737:chemistry*; D055550:Protein Stability; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D052979:Phycobiliproteins; D006861:Hydrogen Peroxide
keywords: Chromophores; Cyanobacteria; Phycobiliproteins; Physico-chemical factors; Stability