title: Cysteine enhances activity and stability of immobilized papain.
abstract: Immobilization of papain on Sepharose 6B in the presence of different concentrations of cysteine affected the enzyme activity depending on cysteine concentration. The maximum specific activity was observed when papain was immobilized with 200 mM cysteine. The immobilization process brought significant enhancement of stability to temperature and extreme pH values with respect to free papain. After immobilization, the optimum temperature of papain activity increased by 20 degrees C (from 60 to 80 degrees C) and its optimum pH activity shifted from 6.5 to 8.0. Catalytic efficiency (k(cat)/K(m)) and specific activity of the immobilized enzyme do not significantly change after immobilization. The temperature profile of this form of immobilized papain showed a broad range of activity compared with both free and immobilized form of papain in the absence of cysteine. This significant behavior in terms of activation energy is also discussed.
authors.affiliation: Department of Biology, Faculty of Science, University of Hormozgan, Bandarabbas, Iran.
authors.forename: Ahmad Abolpour
authors.initials: AA
authors.lastname: Homaei
authors.forename: Reza H
authors.initials: RH
authors.lastname: Sajedi
authors.forename: Reyhaneh
authors.initials: R
authors.lastname: Sariri
authors.forename: Sara
authors.initials: S
authors.lastname: Seyfzadeh
authors.forename: Roberto
authors.initials: R
authors.lastname: Stevanato
mesh_terms: D003432:Cross-Linking Reagents / Q000737:chemistry; D003488:Cyanogen Bromide / Q000737:chemistry; D003545:Cysteine / Q000737:chemistry*; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009994:Osmolar Concentration; D010206:Papain / Q000737:chemistry* / Q000378:metabolism*; D012685:Sepharose / Q000737:chemistry
chemical_list: D003432:Cross-Linking Reagents; D004800:Enzymes, Immobilized; D012685:Sepharose; D010206:Papain; D003545:Cysteine; D003488:Cyanogen Bromide