AIMP1/р43 polypeptide is a multifunctional protein which displays both tRNA binding properties and cytokine activities. Isolated AIMP1/р43 protein is a prospective therapeutic protein in terms of its proapoptotic and antiangiogenic properties. However, AIMP1/р43 is an intrinsically disordered protein that is unstable in solution. In this work we studied the interaction of the recombinant human AIMP1/р43 protein with hydroxypropyl-β-cyclodextrin (HP-β-CD), an oligomer of α-D-glucose residues. Cyclodextrins are intensively used to stabilize biomedical proteins due to the reducing of protein aggregation level, increasing their solubility and resistance to proteolytic enzymes in the blood and gastrointestinal tract. This work represents the investigation of AIMP1/р43 binding with hydroxypropyl-β-cyclodextrin both by fluorescence spectroscopy and computational modeling. It was found that the stability of AIMP1/р43 in the complexes with hydroxypropyl-β-cyclodextrin was increased compared to the free protein. After the binding of HP-β-CD the midpoint of the local conformational transition monitored by Trp271 fluorescence shifted from 43°C to 50°C. This shift in the fluorescence maximum was due to the stabilization of protein structure in the Trp271 environment. Therefore, the use of hydroxypropyl-β-cyclodextrin leads to the stabilization of AIMP1/р43 and opens up the prospect of its use in medical biotechnology.
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