title: Characterization of sea cucumber (stichopus japonicus) ovum hydrolysates: calcium chelation, solubility and absorption into intestinal epithelial cells.
abstract: BACKGROUND
  Sea cucumber (Stichopus japonicus) ovum hydrolysates (SCOHs) chelated with calcium were produced to investigate the characteristics of calcium binding and solubility, as well as to study any effects on calcium absorption by human intestinal epithelial cells.
  
  
  RESULTS
  The results of the present study show that the calcium-binding capacity of SCOHs depended greatly on the type of proteases. The maximum level of Ca binding (0.38 mmol L-1) occurred when trypsin was used, with a peptide yield of 85.7%. Investigation of the possible chelating modes between SCOHs and calcium ions indicated that calcium ions bound to SCOHs primarily via interactions with carboxyl oxygen and amino nitrogen atoms of Glu and Asp and also that the phosphoserine residues might be also responsible for SCOH-calcium chelation. Moreover, SCOH-calcium complexes maintained the solubility of calcium under simulated gastrointestinal digestion, regardless of the presence of dietary components such as oxalate. Furthermore, SCOH-Ca led to higher peak intracellular [Ca2+]iin both Caco-2 cells (338.3 nmol L-1versus 269.6 nmol L-1) and HT-29 cells (373.9 nmol L-1versus 271.7 nmol L-1) than casein phosphopeptide-Ca.
  
  
  CONCLUSIONS
  Carboxyl oxygen and amino nitrogen atoms in the SCOHs could bind calcium ions, forming SCOH-calcium complexes. These complexes improved calcium solubility under simulated gastrointestinal digestion and also promoted calcium absorption in Caco-2 and HT-29 cells. © 2017 Society of Chemical Industry.
authors.affiliation: School of Food Science and Technology, Dalian Polytechnic University, National Engineering Research Center of Seafood, Dalian, PR China.
authors.forename: Na
authors.initials: N
authors.lastname: Sun
authors.affiliation: School of Food Science and Technology, Dalian Polytechnic University, National Engineering Research Center of Seafood, Dalian, PR China.
authors.forename: Pengbo
authors.initials: P
authors.lastname: Cui
authors.affiliation: School of Food Science and Technology, Dalian Polytechnic University, National Engineering Research Center of Seafood, Dalian, PR China.
authors.forename: Songyi
authors.initials: S
authors.lastname: Lin
authors.affiliation: School of Food Science and Technology, Dalian Polytechnic University, National Engineering Research Center of Seafood, Dalian, PR China.
authors.forename: Cuiping
authors.initials: C
authors.lastname: Yu
authors.affiliation: School of Food Science and Technology, Dalian Polytechnic University, National Engineering Research Center of Seafood, Dalian, PR China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Tang
authors.affiliation: School of Food Science and Technology, Dalian Polytechnic University, National Engineering Research Center of Seafood, Dalian, PR China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Wei
authors.affiliation: Department of Animal and Food Sciences, University of Kentucky, Lexington, KT, USA.
authors.forename: Youling
authors.initials: Y
authors.lastname: Xiong
authors.affiliation: School of Food Science and Technology, Dalian Polytechnic University, National Engineering Research Center of Seafood, Dalian, PR China.
authors.forename: Haitao
authors.initials: H
authors.lastname: Wu
mesh_terms: D000818:Animals; D018938:Caco-2 Cells; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D010063:Ovum / Q000737:chemistry*; D011492:Protein Hydrolysates / Q000737:chemistry* / Q000378:metabolism; D012995:Solubility; D047528:Stichopus / Q000737:chemistry* / Q000378:metabolism
chemical_list: D011492:Protein Hydrolysates; D002118:Calcium
keywords: calcium absorption; calcium binding; calcium solubility; sea cucumber ovum