Evidence for the participation of an extra α-helix at β-subunit surface in the thermal stability of Co-type nitrile hydratase.

摘要: Nitrile hydratase (NHase) has attracted considerable attention since it can efficiently catalyze the hydration of nitriles to valuable amides. However, poor stability NHase is one main drawbacks in industrial application. In this study, we compared structural difference between Fe-type and Co-type found that an extra α helix existed at β-subunit surface (defined as β-6th helix). Then, effects were investigated on thermal catalytic kinetics a from Aurantimonas manganoxydans ATCC BAA-1229 (NHase1229). When was deleted or disrupted, NHase1229 reduced 17.6 12.9% wild NHase1229, respectively. Thus, important for NHase. Based characteristics NHase, may be interacted with another α-subunit α-2nd helix) by hydrophobic network just “magnetic suction buckle” enzyme stabilize binding α- β-subunits. The located mouth substrate product tunnel, so plays crucial roles process. Furthermore, swapped thermophilic fragment Pseudonocardia thermophila JCM3095 (NHase1229-Swap). NHase1229-Swap significantly improved, half-life approximately 2.4-fold 40 °C than NHase1229. knowledge useful improving NHases restriction swapping.