title: Calcium ion contribution to thermostability of cyclodextrin glycosyltransferase is closely related to calcium-binding site CaIII.
abstract: In the study, we investigated the contribution of Ca²⁺ to the thermostability of α-cyclodextrin glycosyltransferase (α-CGTase) from Paenibacillus macerans , which has two calcium-binding sites (CaI and CaII), and β-CGTase from Bacillus circulans , which contains an additional calcium-binding site (CaIII), consisting of Ala315 and Asp577. It was found that the contribution of Ca²⁺ to the thermostability of two CGTases displayed a marked difference. Ca²⁺ affected β-CGTase thermostability significantly. After Ca²⁺ was added to β-CGTase solution to a final concentration of 5 mM followed by incubation for 120 min at 60 °C, residual activity of β-CGTase was 88.3%, which was much higher than that without Ca²⁺. However, Ca²⁺ had a small contribution to α-CGTase thermostability. Furthermore, A315D and D577K mutations at CaIII could significantly change the contribution of Ca²⁺ to β-CGTase thermostability. These results suggested that the contribution of Ca²⁺ to CGTase thermostability was closely related to CaIII.
authors: State Key Laboratory of Food Science and Technology, and ‡School of Food Science and Technology, Jiangnan University , Wuxi 214122, People's Republic of China.
authors: Caiming
authors: C
authors: Li
authors: Xiaofeng
authors: X
authors: Ban
authors: Zhengbiao
authors: Z
authors: Gu
authors: Zhaofeng
authors: Z
authors: Li
mesh_terms: D001407:Bacillus / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D004795:Enzyme Stability; D005964:Glucosyltransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D056507:Paenibacillus / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D005964:Glucosyltransferases; C019963:cyclomaltodextrin glucanotransferase; D002118:Calcium