Binding of bivalent ions to actinomycete mannanase is accompanied by conformational change and is a key factor in its thermal stability.

摘要: Abstract The study aimed to define the key factors involved in modulation of actinomycete mannanases. We focused on roles carbohydrate-binding modules (CBMs) and bivalent ions. To investigate effects these factors, two mannanase genes were cloned from Streptomyces thermoluteus (StManII) lividans (SlMan). CBMs fused catalytic domains do not affect thermal stability proteins. CBM2 StManII increased efficiency toward soluble-mannan insoluble-mannan by 25%–36%, CBM10 SlMan 40%–50%. Thermal wild-type mutant enzymes was enhanced calcium manganese. SlMandC also slightly magnesium. These results indicated that ion-binding site responsible for domains. differed kinds Isothermal titration calorimetry revealed domain bound ions with a K 5.39 ± 0.45 × 10 3 –7.56 ± 1.47 × 10  M − 1 , 1.06 ± 0.34 × 10 –3.86 ± 0.94 × 10 . stoichiometry bindings consistent one per molecule enzyme. Circular dichroism spectrum presence induced changes secondary structures enzymes. binding certain ion accompanied different conformational change each ion. Actinomycete mannanases belong GHF5 which contained various hemicellulases; therefore, information obtained applies other