title: A simple technique of preparing stable CLEAs of phenylalanine ammonia lyase using co-aggregation with starch and bovine serum albumin.
abstract: Cross-linked enzyme aggregates (CLEAs) have been recently proposed as an alternative to conventional immobilization methods on solid carriers. However, the low cross-linking efficiency causes the major activity loss and instability in the conventional protocol for CLEA preparation. Herein, the effects of bovine serum albumin and starch addition on the cross-linking efficiency of CLEAs of phenylalanine ammonia lyase (PAL) from Rhodotorula glutinis were evaluated. A co-aggregation strategy was developed to improve cross-linking efficiency by adding starch and bovine serum albumin (BSA). CLEAs of PAL prepared in the presence of BSA and starch (PSB-CLEAs) retained 36 % activity, whereas CLEAs prepared without BSA and starch (PAL-CLEAs) retained only 8 % activity of the starting enzyme preparation. Compared with PAL-CLEAs, the thermal stability of PSB-CLEAs has improved considerably, maintaining 30 % residual activity after 4 h of incubation at 70 °C, whereas the PAL-CLEAs have only 13 % residual activity. PSB-CLEAs also exhibited the expected increased stability of PAL against hydrophilic organic solvents, superior operability, and higher storage stability. The proposed technique of preparing CLEAs using co-aggregation with starch and BSA would rank among the potential strategies for efficiently preparing robust and highly stable enzyme aggregates.
authors.affiliation: Research Center for Fermentation Engineering of Hebei, College of Bioscience and Bioengineering, Hebei University of Science and Technology, 26 YuXiang Street, Shijiazhang, 050000, People's Republic of China. cjd007cn@163.com
authors.forename: Jian Dong
authors.initials: JD
authors.lastname: Cui
authors.forename: Li Mei
authors.initials: LM
authors.lastname: Sun
authors.forename: Lian Lian
authors.initials: LL
authors.lastname: Li
mesh_terms: D003432:Cross-Linking Reagents / Q000737:chemistry*; D004789:Enzyme Activation; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry; D010650:Phenylalanine Ammonia-Lyase / Q000737:chemistry*; D012248:Rhodotorula / Q000201:enzymology*; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D013213:Starch / Q000737:chemistry*
chemical_list: D003432:Cross-Linking Reagents; D004800:Enzymes, Immobilized; D012710:Serum Albumin, Bovine; D013213:Starch; D010650:Phenylalanine Ammonia-Lyase