tailieunhanh - Báo cáo Y học: Purification and properties of the extracellular lipase, LipA, of Acinetobacter sp. RAG-1

An extracellular lipase, LipA, extracted fromAcinetobacter sp. RAG-1 grown on hexadecane was purified and proper-ties of the enzyme investigated. The enzyme is released into the growth medium during the transition to stationary phase. The lipase was harvested from cells grown to sta-tionary phase, and purified with 22% yield and 10-fold purification. The protein demonstrates little affinity for anionexchange resins,withcontaminatingproteins removed by passing crude supernatants over a Mono Q column | Eur. J. Biochem. 269 5771-5779 2002 FEBS 2002 doi Purification and properties of the extracellular lipase LipA of Acinetobacter sp. RAG-1 Erick A. Snellman1 2 Elise R. Sullivan1 3 and Rita R. Colwell1 4 1 Center of Marine Biotechnology University of Maryland Biotechnology Institute MD USA 2 HQ USAFAjDFB USAF Academy CO USA 3Department of Microbiology University of New Hampshire USA 4Department of Cell and Molecular Biology University of Maryland USA An extracellular lipase LipA extracted from Acinetobacter sp. RAG-1 grown on hexadecane was purified and properties of the enzyme investigated. The enzyme is released into the growth medium during the transition to stationary phase. The lipase was harvested from cells grown to stationary phase and purified with 22 yield and 10-fold purification. The protein demonstrates little affinity for anion exchange resins with contaminating proteins removed by passing crude supernatants over a Mono Q column. The lipase was bound to a butyl Sepharose column and eluted in a Triton X-100 gradient. The molecular mass 33 kDa was determined employing SDS PAGE. LipA was found to be stable at pH with optimal activity at . The lipase remained active at temperatures up to 70 C with maximal activity observed at 55 C. LipA is active against a wide range of fatty acid esters of p-nitrophenyl but preferentially attacks medium length acyl chains C6 C8 . The enzyme demonstrates hydrolytic activity in emulsions of both medium and long chain triglycerides as demonstrated by zymogram analysis. RAG-1 lipase is stabilized by Ca2 with no loss in activity observed in preparations containing the cation compared to a 70 loss over 30 h without Ca2 . The lipase is strongly inhibited by EDTA Hg2 and Cu2 but shows no loss in activity after incubation with other metals or inhibitors examined in this study. The protein retains more than 75 of its initial activity after exposure to organic solvents but is rapidly .

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