The structural analysis and the role of calcium binding site for thermal stability in mannanase

► Isothermal titration calorimetry analysis indicated 1 calcium-binding site in actinomycete mannanases. ► The calcium-binding site is near the catalytic cleft. ► One calcium binding site of StMan affects thermal stability and hydrolysis activity. ► One calcium binding site of TfMan affects only thermal stability. ► Successive calcium binding residues are conserved in bacterial GH5 mannanase.