The introduction of foreign peptides into alkaline phosphatase that have a minimal influence on the enzymatic activity of a protein is described in the work. Calculated based on the methods of molecular dynamics the longest surface loops of alkaline phosphatase, which are not adjacent to both active center of a dimeric enzyme and contact surface between its monomers, were used as sites of the introduction of foreign peptides. The length of loops was estimated by several methods. Two loops were used to genetically engineer the introduction of peptides. Experiments demonstrated that the introduction of several peptides after the Ala218 residue of alkaline phosphatase insignificantly influences on the enzyme activity. According to experimental data, the selection of the loop for introducing the foreign peptide can be determined using the methods of molecular dynamics based on calculating the mobility of dihedral angles. In order to create macromolecules with new features by introducing foreign polypeptides in enzymatically active proteins, it is possible in practice to use an estimation of the loop length by means of the methods of molecular dynamics.