Enhanced extracellular expression of Bacillus stearothermophilus α-amylase in Bacillus subtilis through signal peptide optimization, chaperone overexpression and α-amylase mutant selection

Table 4 Characteristics of signal peptides SP_AmyQ′ and SP_YojL

Signal peptides	Hydrophobicity^a	α-Spiral preference^b	N domain charge^c
SP_AmyQ′	41.5	1.41	53.84
SP_YojL	33	0.34	34.96

^aHydrophobicity: The value of the sum of the hydrophobicity of the H domain was calculated using the ProtScale tool (https://web.expasy.org/protscale/pscale/Hphob.Doolittle.html) [42]. The higher the value, the stronger the hydrophobicity
^bα-Spiral preference: The conformational preference of amino acids was determined using the tables in Proteins Structure and Function [43]. The higher the value, the stronger the preference of the α-spiral
^cN domain charge: The sum of the charges on the N-terminal amino acid of the signal peptide was calculated from the sum of the isoelectric points of the N-terminal amino acids

ISSN: 1475-2859