Small surfactant-like peptides can drive soluble proteins into active aggregates

Table 1 Enzymatic activities of the fusion proteins produced in E.coli

Enzyme	Activity (U/ml)¹		Percent of activity in insoluble fraction (PDE)²	Specific activity (U/mg enzyme)³	Specific activity relative to native enzyme (SArN)
	Soluble fractions	Insoluble fractions
AMA-native⁴	734.4 ± 37.5	9.63 ± 2.29	1.3%	1563	100%
AMA-L₆KD	236.0 ± 49.0	361.7 ± 59.5	60.5%	1447	92.6%
LipA-native⁵	20.1 ± 0. 5	2.7 ± 0.3	12.0%	96	100%
LipA-L₆KD	5.9 ± 0.6	23.8 ± 3.1	80.2%	29	30.2%
XynB-native⁵	398.8 ± 9.7	136.2 ± 17.0	25.4%	1286	100%
XynB-L₆KD	34.0 ± 0.8	174.5 ± 22.9	83.7%	329	25.6%

¹Cells were collected 6 h after IPTG induction. 1 ml soluble enzyme was extracted from 10 OD₆₀₀ of cells; the insoluble fraction was also from 10 OD₆₀₀ of cells and then re-suspended in 1 ml of lysis buffer. Enzymes amounts were calculated based on SDS-PAGE with serial concentrations of BSA as standards. AMA, Aspergillus fumigatus amadoriase II; LipA, Bacillus subtilis lipase A; XynB, Bacillus pumilus β-xylosidase.
²Percentage of the activity found in the insoluble fraction relative to the total activity in the cell lysate (soluble and insoluble fractions combined), also referred to as pulling down efficiency (PDE).
³For the L₆KD fusion, the value concerns the enzyme in the insoluble fraction (more specifically, enzyme aggregate); for the native enzyme, the value concerns the enzyme in the soluble fraction.
⁴Data cited form reference [9].
⁵Data cited form reference [8].

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