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PDBsum entry 5e9a
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References listed in PDB file
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Key reference
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Title
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Cloning, Expression and structural stability of a cold-Adapted β-Galactosidase from rahnella sp. R3.
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Authors
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Y.Fan,
X.Hua,
Y.Zhang,
Y.Feng,
Q.Shen,
J.Dong,
W.Zhao,
W.Zhang,
Z.Jin,
R.Yang.
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Ref.
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Protein Expr Purif, 2015,
115,
158-164.
[DOI no: ]
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PubMed id
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Abstract
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A novel gene was isolated for the first time from a psychrophilic gram-negative
bacterium Rahnella sp. R3. The gene encoded a cold-adapted β-galactosidase
(R-β-Gal). Recombinant R-β-Gal was expressed in Escherichia coli BL21 (DE3),
purified and characterized. R-β-gal belongs to the glycosyl hydrolase family
42. Circular dichroism spectrometry of the structural stability of R-β-Gal with
respect to temperature indicated that the secondary structures of the enzyme
were stable to 45°C. In solution, the enzyme was a homo-trimer and was active
at temperatures as low as 4°C. The enzyme did not require the presence of metal
ions to be active, but Mg(2+), Mn(2+), and Ca(2+) enhanced its activity
slightly, whereas Fe(3+), Zn(2+) and Al(3+) appeared to inactive it. The
purified enzyme displayed K(m) values of 6.5 mM for ONPG and 2.2mM for lactose
at 4°C. These values were lower than the corresponding K(m)s reported for other
cold-adapted β-Gals.
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