title: Characterization of photosystem I from spinach: effect of solution pH.
abstract: Our previous work has demonstrated the isolation of photosystem I (PSI) from spinach using ultrafiltration with a final purity of 84%. In order to get a higher purity of PSI and more importantly to develop a practical bioseparation process, key physiochemical properties of PSI and their dependence on operational parameters must be assessed. In this study, the effect of solution pH, one of the most important operating parameters for membrane process, on the property of PSI was examined. Following the isolation of crude PSI from spinach using n-dodecyl-beta-D: -maltoside as detergent, the isoelectric point, aggregation size, zeta potential, low-temperature fluorescence, atomic force microscopy imaging, secondary structure, and thermal stability were determined. Solution pH was found to have a significant effect on the activity, aggregation size and thermal stability of PSI. The results also suggested that the activity of PSI was related to its aggregation size.
authors.affiliation: Center for Bioengineering and Biotechnology, China University of Petroleum (East China), Qingdao 266555, People's Republic of China. jianguoliu@upc.edu.cn
authors.forename: Jianguo
authors.initials: J
authors.lastname: Liu
authors.forename: Xuefang
authors.initials: X
authors.lastname: Zhang
authors.forename: Meng
authors.initials: M
authors.lastname: Wang
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.forename: Meiwen
authors.initials: M
authors.lastname: Cao
authors.forename: Jianren
authors.initials: J
authors.lastname: Lu
authors.forename: Zhanfeng
authors.initials: Z
authors.lastname: Cui
mesh_terms: D002462:Cell Membrane / Q000737:chemistry; D003902:Detergents / Q000737:chemistry; D005453:Fluorescence; D005960:Glucosides / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D018625:Microscopy, Atomic Force; D045331:Photosystem I Protein Complex / Q000737:chemistry* / Q000302:isolation & purification; D010940:Plant Proteins / Q000737:chemistry / Q000302:isolation & purification*; D055550:Protein Stability; D017433:Protein Structure, Secondary; D012996:Solutions / Q000737:chemistry; D018724:Spinacia oleracea / Q000737:chemistry*; D013696:Temperature; D020524:Thylakoids / Q000737:chemistry; D014462:Ultrafiltration / Q000379:methods
chemical_list: D003902:Detergents; D005960:Glucosides; D045331:Photosystem I Protein Complex; D010940:Plant Proteins; D012996:Solutions; C040358:dodecyl maltoside