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- Fernandes, S, et al.
(författare)
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Beta-galactosidase from a cold-adapted bacterium: purification, characterization and application for lactose hydrolysis.
- 2002
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Ingår i: Applied Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 1432-0614 .- 0175-7598. ; 58:3, s. 313-321
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Tidskriftsartikel (refereegranskat)abstract
- The enzyme beta-galactosidase was purified from a cold-adapted organism isolated from Antarctica. The organism was identified as a psychrotrophic Pseudoalteromonas sp. The enzyme was purified with high yields by a rapid purification scheme involving extraction in an aqueous two-phase system followed by hydrophobic interaction chromatography and ultrafiltration. The beta-galactosidase was optimally active at pH 9 and at 26 degrees C when assayed with o-nitrophenyl-beta-D-galactopyranoside as substrate for 2 min. The enzyme activity was highly sensitive to temperature above 30 degrees C and was undetectable at 40 degrees C. The cations Na+, K+, Mg2+ and Mn2+ activated the enzyme while Ca2+, Hg2+, Cu2+ and Zn2+ inhibited activity. The shelf life of the pure enzyme at 4 degrees C was significantly enhanced in the presence of 0.1% (w/v) polyethyleneimine. The pure beta-galactosidase was also evaluated for lactose hydrolysis. More than 50% lactose hydrolysis was achieved in 8 h in buffer at an enzyme concentration of 1 U/ml, and was increased to 70% in the presence of 0.1% (w/v) polyethyleneimine. The extent of lactose hydrolysis was 40-50% in milk. The enzyme could be immobilized to Sepharose via different chemistries with 60-70% retention of activity. The immobilized enzyme was more stable and its ability to hydrolyze lactose was similar to that of the soluble enzyme.
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| 2. |
- Mphahlele M.J, Fernandes M.A, El-Nahas A.M, Ottosson H, Ndlovu S.M, Sithole H.M, Dladla B.S, De Waal D.
(författare)
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Solution Phase, Solid State and Computational Structural Studies of 2-Aryl-3-bromoquinolin-4(1H)-one Derivatives
- 2002
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Ingår i: J. Chem. Soc., Perkins Trans. 2. ; , s. 2159-2164
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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