An In silico Search for the Sites of Potential Binding with Charged and Hydrophobic Carriers in the Molecules of Endoinulinase from Aspergillus ficuum and Exoinulinase from Aspergillus awamori

Abstract

Abstract—The composition and location of charged and hydrophobic amino-acid residues in the endoinulinase (3SC7) and exoinulinase (1Y4W) molecules have been investigated. The percentage of different types of amino acids on the surface of enzyme molecules has been determined. It has been found that the charged and hydrophobic amino-acid residues are distributed unevenly over the surface of the molecules and form the sites of local clusters. It has been shown that positively charged carriers are the most promising for the immobilization of endoinulinases; they may interact with one of the following sites on the surface of the enzyme molecules, which are remote from the active center and contain Glu239, Glu243, Glu246, Glu247, and Asp275 (site 1); Asp399, Asp424, Glu433, Glu452, Glu453, Asp454, and Glu497 (site 2); Asp37, Asp92, Glu93, and Glu516 (site 3). Negatively charged carriers are most promising for exoinulinase, because the binding sites for these carriers that contain Lys225 and Lys247 (site 1); His80, Lys84, Lys118, and Lys121 (site 2); Lys381, Arg382, Arg387, Lys390, Lys407, Lys415, Lys417, Lys479, Arg526, and Lys531 (site 3) are located on the surface of the enzyme molecules remote from the active center. Hydrophobic carriers are the least promising, because the amino-acid residues on the surface of the enzymes, to which the polymers can bind, are in the area of the active center; these residues are Tyr39, Pro62, Val66, Leu172, Gly196, and Gly259, in the case of endoinulinase; and Tyr47, Trp65, Pro85, Val86, Leu89, Leu161, Pro232, Gly237, Pro266, Pro270, Val293, Pro298, Gly299, and Gly320, in the case of exoinulinase.