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Table 5 Effect of additives used in the reaction mixture on laccase thermal stability in aqueous medium composed of acetate buffer (0.1 M, pH 5.0), using syringaldazine as substrate

From: Lyoprotection and stabilization of laccase extract from Coriolus hirsutus, using selected additives

Additive

Relative concentrationa

Residual laccase activity (%)b

4 °C

25 °C

37 °C

50 °C

None

 

81.0 (3.0)c

65.7 (4.2)

49.0 (7.3)

4.1 (0.7)

CuSO4

0.002

116.4 (1.6)

88.0 (5.1)

62.8 (9.6)

12.6 (4.6)

PEG-8000

0.02

112.5 (4.0)

96.2 (1.3)

99.3 (7.6)

11.8 (0.3)

Glycerol

0.4

114.1 (10.1)

94.0 (10.8)

79.2 (1.3)

9.8 (0.4)

  1. aRelative concentration of the additive, expressed in percent (w/v), was the one at which the laccase specific activity was at its optimum
  2. bResidual laccase activity (%) was calculated by dividing the specific activity (nmol product/mg protein/min) of a given sample after 168 h of incubation at a defined temperature to that at time 0, multiplied by 100. The enzyme activity was assayed with syringaldazine as substrate
  3. cRelative percentage standard deviation was defined as the standard deviation of laccase triplicate trial divided by their respective means, multiplied by 100
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