title: High-capacity calcium-binding chitinase III from pomegranate seeds (Punica granatum Linn.) is located in amyloplasts.
abstract: We have recently identified a new class III chitinase from pomegranate seeds (PSC). Interestingly, this new chitinase naturally binds calcium ions with high capacity and low affinity, suggesting that PSC is a Ca-storage protein. Analysis of the amino acid sequence showed that this enzyme is rich in acidic amino acid residues, especially Asp, which are responsible for calcium binding. Different from other known chitinases, PSC is located in the stroma of amyloplasts in pomegranate seeds. Transmission electron microscopy (TEM) analysis indicated that the embryonic cells of pomegranate seeds are rich in calcium ions, most of which are distributed in the stroma and the starch granule of the amyloplasts, consistent with the above idea that PSC is involved in calcium storage, a newly non-defensive function.
authors: CAU & ACC Joint-Laboratory of Space Food, College of Food Science & Nutritional Engineering, China Agricultural University, Key Laboratory of Functional Dairy, Beijing, China.
authors: Chenyan
authors: C
authors: Lv
authors: Taro
authors: T
authors: Masuda
authors: Haixia
authors: H
authors: Yang
authors: Lei
authors: L
authors: Sun
authors: Guanghua
authors: G
authors: Zhao
mesh_terms: D002118:Calcium / Q000378:metabolism; D002688:Chitinases / Q000235:genetics / Q000378:metabolism*; D029561:Lythraceae / Q000201:enzymology* / Q000235:genetics; D046529:Microscopy, Electron, Transmission; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018087:Plastids / Q000201:enzymology*; D017434:Protein Structure, Tertiary; D012639:Seeds / Q000201:enzymology* / Q000648:ultrastructure; D013213:Starch / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D013213:Starch; D002688:Chitinases; C110892:chitinase, class III; D002118:Calcium