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

2017 ◽  
Vol 65 (44) ◽  
pp. 9782-9789 ◽  
Author(s):  
Na Sun ◽  
Ziqi Jin ◽  
Dongmei Li ◽  
Hongjie Yin ◽  
Songyi Lin
Keyword(s):  
Calcium Binding ◽  
Calcium Absorption ◽  
Binding Mode ◽  
Egg White ◽  
Absorption Studies

Effect of hypophysectomy on calcium transport by rat duodenum.

1977 ◽  
Vol 232 (2) ◽  
pp. E229
Author(s):  
E L Krawitt ◽  
A S Kunin ◽  
H W Sampson ◽  
B F Bacon
Keyword(s):  
Calcium Transport ◽  
Calcium Absorption ◽  
Plasma Flux ◽  
Perfusion Technique ◽  
Intestinal Length ◽  
Absorption Studies ◽  
Luminal Perfusion ◽  
Rat Duodenum

To examine the effect of hypophysectomy on intestinal calcium absorption, studies were performed on immature rats 7, 14, and 21 days after hypophysectomy. Duodenal calcium transport was measured in vitro utilizing everted gut sacs and in vivo by a luminal perfusion technique. Hypophysectomy produced no differences in the ability of everted gut sacs to transport calcium. Similarly, when in vivo transport data were expressed on the basis of intestinal length, no significant differences were noted. However, when transport data were expressed on the basis of mucosal weight, increases in absorption and lumen-to-plasma fluxes were apparent in hypophysectomized animals. No differences were seen in plasma-to-lumen fluxes. The results indicate that when the transport data are corrected for mass of intestinal mucosa, the duodenum from hypophysectomized animals absorbs calcium more avidly due to an increase in lumen-to-plasma flux.

scholarly journals Elucidating the Calcium-Binding Site, Absorption Activities, and Thermal Stability of Egg White Peptide–Calcium Chelate

Foods ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2565
Author(s):  
Zhijie Bao ◽  
Penglin Zhang ◽  
Na Sun ◽  
Songyi Lin
Keyword(s):  
Calcium Binding ◽  
Calcium Absorption ◽  
Binding Capacity ◽  
Egg White ◽  
Absorption Capacity ◽  
Spherical Particles ◽  
Calcium Binding Site ◽  
Peptide Bonds ◽  
High Calcium ◽  
Α Helix

With the current study, we aimed to determine the characteristics and calcium absorption capacity of egg white peptide–calcium complex (EWP-Ca) and determine the effect of sterilization on EWP-Ca to study the possibility of EWP-Ca as a new potential calcium supplement. The results of SEM and EDS showed a high calcium chelating ability between EWP and calcium, and the structure of EWP-Ca was clustered spherical particles due its combination with calcium. The FTIR and Raman spectrum results showed that EWP could chelate with calcium by carboxyl, phosphate, and amino groups, and peptide bonds may also participate in peptide–calcium binding. Moreover, the calcium absorption of EWP-Ca measured by the intestinal everted sac model in rats was 32.38 ± 6.83 μg/mL, significantly higher than the sample with CaCl2, and the mixture of EWP and Ca (p < 0.05) revealed appropriate calcium absorption capacity. The fluorescence spectra and CD spectra showed that sterilization caused a decrease in the content of α-helix and β-sheet and a significant increase in β-turn (p < 0.05). Sterilization changed the EWP-Ca structure and decreased its stability; the calcium-binding capacity of EWP-Ca after sterilization was decreased to 41.19% (p < 0.05). Overall, these findings showed that EWP could bind with calcium, form a peptide–calcium chelate, and serve as novel carriers for calcium supplements.

Mucosal calcium uptake by rat cecum: identity with transcellular calcium absorption

1983 ◽  
Vol 244 (6) ◽  
pp. G618-G622
Author(s):  
H. N. Nellans ◽  
R. S. Goldsmith
Keyword(s):  
Calcium Binding ◽  
Calcium Uptake ◽  
Calcium Absorption ◽  
Calcium Influx ◽  
Maximal Velocity ◽  
Similar Reduction ◽  
High Calcium ◽  
Wide Range ◽  
Rat Cecum

Unidirectional intestinal calcium uptake (JCame) at the mucosal surface of rat cecum was investigated in vitro with intact tissue. Uptake is linear for 2–3 min with no indication of rapid calcium binding. Kinetic parameters reveal a maximal velocity of 333 nmol . cm-2 . h-1 with a half-maximal concentration of 0.98 mM. High-calcium diet decreased JCame by more than 60% with respect to both control and low-calcium diets; 1 mM N-ethylmaleimide caused a similar reduction. The activation energy of JCame is significantly less than that of transepithelial mucosal-to-serosal calcium absorption. Mucosal uptake was compared with transepithelial calcium fluxes in rat cecum and revealed a 1:1 correlation over a wide range of transport rates. These results are interpreted to implicate a feedback control system between basolateral calcium efflux and brush-border calcium influx.

scholarly journals Promoting the Calcium-Uptake Bioactivity of Casein Phosphopeptides in vitro and in vivo

2021 ◽  
Vol 8 ◽  
Author(s):  
Guo Liu ◽  
Baoyan Guo ◽  
Shengwei Sun ◽  
Minna Luo ◽  
Fei Liu ◽  
...  
Keyword(s):  
Calcium Binding ◽  
Calcium Transport ◽  
Calcium Uptake ◽  
Calcium Absorption ◽  
Serum Alkaline Phosphatase ◽  
Binding Capacity ◽  
Animal Experiments ◽  
Casein Phosphopeptides

Casein phosphopeptides have been studied widely for their ability to chelate calcium. However, systematic studies on the effects of casein phosphopeptides (CPP) on calcium absorption in vitro and in vivo are scarce. The purities of two commercially available products, CPP1 and CPP2, are 18.37 and 25.12%, respectively. Here, the in vitro calcium binding capacity of CPP2 was 142.56 ± 7.39 mg/g, which was higher than that of CPP1 (107.15 ± 6.27 mg/g). The calcium transport results in a Caco-2 monolayer model indicated that, relative to controls, CPP1 and CPP2 increased calcium transport by 21.78 and 53.68%, respectively. Subsequent animal experiments showed that the CPP2-Ca-H group (1% Ca, 0.4% CPP2) had significant increases in the femur index, serum Ca2+ and serum osteocalcin levels, and femoral Ca content. The CPP2-Ca-H animal also had decreased serum alkaline phosphatase levels, parathyroid hormone content, and urinary pyridinoline content. Overall, our results demonstrated that CPP2 had stronger effects on promoting calcium uptake than CPP1.

scholarly journals Tilapia Protein Hydrolysate Enhances Transepithelial Calcium Transport in Caco2 cells

2019 ◽  
Vol 9 (10) ◽  
pp. 678 ◽  
Author(s):  
Nootjaree Buaduang ◽  
Worrapanit Chansuwan ◽  
Nongporn Hutadilok Towatana ◽  
Zhe Yang ◽  
Nualpun Sirinupong
Keyword(s):  
Calcium Binding ◽  
Calcium Transport ◽  
Calcium Absorption ◽  
Protein Hydrolysate ◽  
Binding Activity ◽  
Leafy Vegetables ◽  
Cell Permeability ◽  
Calcium Balance ◽  
Food Components

Background: Potent calcium uptake is essential for calcium balance and normal health. Prolonged low intake of calcium is associated with osteoporosis, dental changes, cataracts, and alterations in the brain. However, calcium is difficult to be directly absorbed from the food due to the insoluble calcium salt precipitation that occurs in the intestinal environment. Methods: Tilapia protein hydrolysate (TPH) was prepared by alcalase digestion. The Calcium-binding activity was measured using calcium colorimetric assay, the absorption at 612 nm. The interaction between TPH and calcium was examined by spectroscopic analysis, ultraviolet absorption and fluorescence measurement. TPH-calcium-binding stability in the human digestion system was evaluated by in vitro pepsin-pancreatin hydrolysis simulating human gastric and intestinal digestion. The effects of food components on TPH-calcium-binding activity was also analyzed. The enhancement of transepithelial calcium transport by TPH was determined by in vitro Caco2 epithelial cell-like monolayer. Results: TPH produced from Nile tilapia (Oreochromis niloticus) exhibited calcium-binding activity. It was the peptides in the hydrolysate that contributed to calcium-binding since the spectroscopic changes induced by calcium were characteristic of peptide bonds and tryptophan residues. The calcium binding of TPH was compatible with food matrices. Most food components including saccharides, amino acids and vitamins showed positive or no effects on calcium-binding. The calcium-binding of TPH was also stable in the simulated gastrointestinal digestion system. Pepsin and pancreatin did not considerably change the calcium-binding activity of TPH. Of note, TPH reduced precipitation of calcium by oxalate and phytate, the two most anti-nutritional factors present in green leafy vegetables. Finally, we showed that TPH significantly promoted transepithelial calcium transport in the Caco-2 cell permeability model. Conclusions: Tilapia protein hydrolysate produced by alcalase digestion possessed calcium-binding activity and prevent precipitation of calcium by a mineral chelating agent as well as enhanced transepithelial calcium transport in Caco2 cell. The result implicated the potential of TPH as a functional food ingredient for promoting calcium absorption. Keywords: Tilapia protein hydrolysate; Calcium binding peptides; Calcium absorption

Studies of Calcium Absorption in Man Using a CD-2 Whole-Body Counter

1977 ◽  
Vol 16 (04) ◽  
pp. 163-167
Author(s):  
K. Bakos ◽  
Věra Wernischová
Keyword(s):  
Calcium Absorption ◽  
Whole Body ◽  
Control Group ◽  
Absorption Process ◽  
Whole Body Counter ◽  
Absorption Studies ◽  
Body Counting ◽  
Calcium Load ◽  
Calcium Malabsorption ◽  
Whole Body Counting

SummaryWhole-body counting makes an important contribution of radioisotope techniques to ȁEin vivo“ absorption studies, in comparison with other methods. In a large number of subjects, the method was tested for its usefulness in the diagnosis of calcium malabsorption. The effects of drugs, of the calcium load in the gut and of the whole-body content of calcium on the absorption process were studied in a control group.

Design, Synthesis, Molecular Docking and Biological Evaluation of 1-(benzo[d]thiazol-2-ylamino)(phenyl)methyl)naphthalen-2-ol Derivatives as Antiproliferative Agents

2019 ◽  
Vol 16 (10) ◽  
pp. 837-845
Author(s):  
Sandhya Jonnala ◽  
Bhaskar Nameta ◽  
Murthy Chavali ◽  
Rajashaker Bantu ◽  
Pallavi Choudante ◽  
...  
Keyword(s):  
Molecular Docking ◽  
Inhibitory Activity ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Mouse Skin ◽  
Coupling Reaction ◽  
Binding Mode ◽  
Biological Evaluation ◽  
Design Synthesis

A class of 1-((benzo[d]thiazol-2-ylamino)(phenyl)methyl)naphthalen-2-ol derivatives (4a-t) has been synthesized in good yields through a three component coupling reaction. The newly synthesized compounds were evaluated for their in vitro antiproliferative activity against five cell lines such as DU145 (human prostate cancer), MDA-MB-B231 (human breast cancer), SKOV3 (human ovarian cancer), B16-F10 (mouse skin melanoma) and CHO-K1 (Chinese hamster ovary cells), a noncancerous cell line. In vitro inhibitory activity indicates that compounds 4a, 4b, 4c, 4d, 4g, 4j, and 4o exhibited potent anti-proliferative behavior. Among them, compounds 4g, 4j and 4o found to be the most active members exhibiting remarkable growth inhibitory activity. Molecular docking facilitates to investigate the probable binding mode and key active site interactions in tubulins α and β proteins. The docking results are complementary to experimental results.

scholarly journals The Repurposed Drugs Suramin and Quinacrine Cooperatively Inhibit SARS-CoV-2 3CLpro In Vitro

Viruses ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 873
Author(s):  
Raphael J. Eberle ◽  
Danilo S. Olivier ◽  
Marcos S. Amaral ◽  
Ian Gering ◽  
Dieter Willbold ◽  
...  
Keyword(s):  
Binding Mode ◽  
Drug Candidates ◽  
Main Protease ◽  
Ic50 Values ◽  
Repurposed Drugs ◽  
Antiparasitic Drugs ◽  
Inhibitory Potential ◽  
Dynamics Simulations ◽  
Micromolar Range

Since the first report of a new pneumonia disease in December 2019 (Wuhan, China) the WHO reported more than 148 million confirmed cases and 3.1 million losses globally up to now. The causative agent of COVID-19 (SARS-CoV-2) has spread worldwide, resulting in a pandemic of unprecedented magnitude. To date, several clinically safe and efficient vaccines (e.g., Pfizer-BioNTech, Moderna, Johnson & Johnson, and AstraZeneca COVID-19 vaccines) as well as drugs for emergency use have been approved. However, increasing numbers of SARS-Cov-2 variants make it imminent to identify an alternative way to treat SARS-CoV-2 infections. A well-known strategy to identify molecules with inhibitory potential against SARS-CoV-2 proteins is repurposing clinically developed drugs, e.g., antiparasitic drugs. The results described in this study demonstrated the inhibitory potential of quinacrine and suramin against SARS-CoV-2 main protease (3CLpro). Quinacrine and suramin molecules presented a competitive and noncompetitive inhibition mode, respectively, with IC50 values in the low micromolar range. Surface plasmon resonance (SPR) experiments demonstrated that quinacrine and suramin alone possessed a moderate or weak affinity with SARS-CoV-2 3CLpro but suramin binding increased quinacrine interaction by around a factor of eight. Using docking and molecular dynamics simulations, we identified a possible binding mode and the amino acids involved in these interactions. Our results suggested that suramin, in combination with quinacrine, showed promising synergistic efficacy to inhibit SARS-CoV-2 3CLpro. We suppose that the identification of effective, synergistic drug combinations could lead to the design of better treatments for the COVID-19 disease and repurposable drug candidates offer fast therapeutic breakthroughs, mainly in a pandemic moment.

Preparation of dextran–casein phosphopeptide conjugates, evaluation of its calcium binding capacity and digestion in vitro

2021 ◽  
pp. 129332
Author(s):  
Lan Jiang ◽  
Shuhong Li ◽  
Nan Wang ◽  
Shuang Zhao ◽  
Yue Chen ◽  
...  
Keyword(s):  
Calcium Binding ◽  
Binding Capacity ◽  
Casein Phosphopeptide
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