N‑(6‑Aminohexyl)‑5‑chloro‑1‑naphthalenesulfonamide, a centrin antagonist, inhibits Tb/peptides-binding properties.

N‑(6‑Aminohexyl)‑5‑chloro‑1‑naphthalenesulfonamide (W-7), a kind of adjuvant chemotherapy, can bind to calmodulin and inhibit Ca/calmodulin-regulated enzyme activities and cell proliferation. Similar to calmodulin, euplotes octocarinatus centrin (EoCen) belongs to EF-hand superfamily of calcium-binding proteins. It is associated with nucleotide excision repair (NER), cell division cycle and ciliogenesis. In the present study, the comparative interaction of W-7 with EoCen was first examined by using various spectroscopic, calorimetric methods and molecular docking. The obtain results recommend that only one W-7 molecule is identified binding to the C-terminal hydrophobic pocket of centrin that normally plays a role in anchoring targets. Methyl groups of Ala126, Met141, Ile161 and M162 of C-terminal may react with W-7 chloronaphthalene ring, other aliphatic or aromatic side-chains in a deep hydrophobic pocket of protein. Circular dichroism (CD) and fluorescence lifetime experiments reveal that W-7 triggers a conformational change of centrin. As a result, W-7 is identified to be an antagonist of centrin. It appears to inhibit the centrin-mediated activation of target proteins by blocking the hydrophobic pocket. Moreover, the complex formation leads to affinity decrease of Tb binding to C-terminal of protein and self-assembly affected. Our present study provides the first view of centrin recognizing a naphthalene-sulfonamide derivative. It is proposed that W-7 and its analogues can serve as a useful tool for research on the participation of centrin in biological processes and cell biology-related studies.