Part:BBa_K3606000
CaAP, Calcium Absorption Peptide
CAAP(Calcium Absorption Peptide) is an artificially designed peptide to promote calcium absorption of intestinal epithelial cells.
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12COMPATIBLE WITH RFC[12]
- 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25INCOMPATIBLE WITH RFC[25]Illegal AgeI site found at 78
- 1000COMPATIBLE WITH RFC[1000]
CAAP(Calcium Absorption Peptide) is an artificially designed peptide to promote calcium absorption of intestinal epithelial cells. The sequence design of CAAP is based on calcium-binding peptides, a class of oligopeptides capable of chelating calcium, which have been found in hen egg yolk, cow milk casein, whey, soy, wheat germ and tilapia fish, etc. They have drawn a great deal of attention from researchers for their ability to promote calcium uptake in Caco-2 cells, indicating that they could function as a novel kind of nutritional supplementary with high efficiency to help address the calcium deficiency problem nowadays, especially for the elderly. Moreover, the biosafety of these oligopeptides can be guaranteed because they are derived from natural plant or animal food.
The whole sequence of CAAP contains 5 different calcium-binding peptides: GPAGPHGPVG, FDHIVY, YQEPVIAPKL[1], NDEELNK[2], and DHTKE[3], which are all experimentally proved to increase calcium absorption prominently either in vivo or in vitro. After calcium ion is spontaneously bound to the Asp or Glu residue of the peptides, the calcium-peptide complex can facilitate the calcium influx into the cytoplasm of intestinal epithelial cells.
To efficiently express CAAP in the engineered strains(E.coli) and allow them to play a role when secreted into the extracellular space, sequences of the 5 mentioned oligopeptides are linked together through FR junctions(Phe-Arg). Hence, they could be expressed in the form of a whole peptide in the engineered bacteria and later cleaved into functional oligopeptides in the presence of digestive enzymes in the intestinal lumen.
References
[1] Three Newly Isolated Calcium-Chelating Peptides from Tilapia Bone Collagen Hydrolysate Enhance Calcium Absorption Activity in Intestinal Caco-2 Cells. Wanwen Liao, Hui Chen, Wengang Jin, Zhennai Yang, Yong Cao, and Jianyin Miao. Journal of Agricultural and Food Chemistry 2020 68 (7), 2091-2098.
[2] In vitro digestion profile and calcium absorption studies of a sea cucumber ovum derived heptapeptide–calcium complex. Pengbo Cui, Songyi Lin, Ziqi Jin, Beiwei Zhu, Liang Song and Na Sun. Food Funct., 2018,9, 4582-4592.
[3] An Exploration of the Calcium-Binding Mode of Egg White Peptide, Asp-His-Thr-Lys-Glu, and In Vitro Calcium Absorption Studies of Peptide–Calcium Complex. Na Sun, Ziqi Jin, Dongmei Li, Hongjie Yin, and Songyi Lin. Journal of Agricultural and Food Chemistry 2017 65 (44), 9782-9789.
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