title: A stable and functional single peptide phycoerythrin (15.45 kDa) from Lyngbya sp. A09DM.
abstract: A functional and stable truncated-phycoerythrin (T-PE) was found as a result of spontaneous in vitro truncation. Truncation was noticed to occur during storage of purified native-phycoerythrin (N-PE) isolated from Lyngbya sp. A09DM. SDS and native-PAGE analysis revealed the truncation of N-PE, containing α (19.0 kDa)--and β (21.5 kDa)--subunits to the only single peptide of ∼15.45 kDa (T-PE). The peptide mass fingerprinting (PMF) and MS/MS analysis indicated that T-PE is the part of α-subunit of N-PE. UV-visible absorption peak of N-PE was found to split into two peaks (540 and 565 nm) after truncation, suggesting the alterations in its folded state. The emission spectra of both N-PE and T-PE show the emission band centered at 581 nm (upon excitation at 559 nm) suggested the maintenance of fluorescence even after significant truncation. Urea-induced denaturation and Gibbs-free energy (ΔGD°) calculations suggested that the folding and structural stability of T-PE was almost similar to that of N-PE. Presented bunch of evidences revealed the truncation in N-PE without perturbing its folding, structural stability and functionality (fluorescence), and thereby suggested its applicability in fluorescence based biomedical techniques where smaller fluorescence molecules are more preferable.
authors.affiliation: BRD School of Biosciences, Sardar Patel University, Vadtal Road, Satellite Campus, Post Box No. 39, Vallabh Vidyanagar 388120, Gujarat, India. Electronic address: ravi123sonani@gmail.com.
authors.forename: Ravi Raghav
authors.initials: RR
authors.lastname: Sonani
authors.affiliation: BRD School of Biosciences, Sardar Patel University, Vadtal Road, Satellite Campus, Post Box No. 39, Vallabh Vidyanagar 388120, Gujarat, India. Electronic address: raj_rastogi@rediffmail.com.
authors.forename: Rajesh Prasad
authors.initials: RP
authors.lastname: Rastogi
authors.affiliation: BRD School of Biosciences, Sardar Patel University, Vadtal Road, Satellite Campus, Post Box No. 39, Vallabh Vidyanagar 388120, Gujarat, India.
authors.forename: Meghna
authors.initials: M
authors.lastname: Joshi
authors.affiliation: BRD School of Biosciences, Sardar Patel University, Vadtal Road, Satellite Campus, Post Box No. 39, Vallabh Vidyanagar 388120, Gujarat, India. Electronic address: datta_madamwar@yahoo.com.
authors.forename: Datta
authors.initials: D
authors.lastname: Madamwar
mesh_terms: D000595:Amino Acid Sequence; D000458:Cyanobacteria / Q000737:chemistry*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry* / Q000302:isolation & purification; D010799:Phycoerythrin / Q000737:chemistry* / Q000302:isolation & purification; D017510:Protein Folding / Q000187:drug effects; D055550:Protein Stability / Q000187:drug effects; D021122:Protein Subunits / Q000737:chemistry; D014508:Urea / Q000494:pharmacology
chemical_list: D010446:Peptide Fragments; D021122:Protein Subunits; D010799:Phycoerythrin; D014508:Urea
keywords: In vitro truncation; Phycoerythrin; Structural stability