A milk-derived phosphorylated peptide with the activity of promoting intestinal iron absorption and its application in the preparation of an iron supplement

Abstract

The present application relates to a milk-derived phosphorylated peptide with the activity of improving intestinal iron absorption and its application in the preparation of iron supplements. The sequence of the milk-derived phosphorylated peptide is EESITRINKKIE, and the glutamic acid at the amino terminal of the sequence is connected with 1-3 phosphoserines. The milk-derived phosphorylated peptide can be combined with Fe 2+ Specifically bound, strong iron chelating ability, and can significantly improve the iron transport amount in the Caco-2 small intestinal epithelial cell model, thereby having good activity of improving intestinal iron absorption, and can be widely applied in the fields of drugs, health care products or food.

Description

Technical Field

[0001] The present invention relates to the field of small molecule peptides, and more particularly to a milk-derived phosphorylated peptide capable of enhancing intestinal iron absorption activity and application thereof in the preparation of an iron supplement. Background Art

[0002] Iron is an essential trace element for the human body, existing in both heme and non-heme forms. Iron is primarily involved in the production of hemoglobin and oxygen transport. Adequate iron supplementation is essential for adequate hemoglobin production. Iron deficiency can severely impact human health, leading to iron-deficiency anemia and neurological disorders.

[0003] Many staple foods in the diet (cereals, corn, rice, etc.) typically contain phosphoric acid, phytic acid, and oxalic acid, which complex and precipitate with iron ions in the intestines, affecting the intestinal absorption and utilization of iron ions, and are the main factors leading to iron deficiency. In addition, the intake of other metal ions also affects the bioavailability of iron in the human body. For example, when dietary calcium is consumed in large quantities, it significantly reduces intestinal absorption of iron in a dose-dependent manner.

[0004] To address the problem of iron deficiency, various iron supplements have appeared on the market, including inorganic iron (ferrous sulfate), organic iron (ferric gluconate), amino acid iron chelates, and food-derived iron chelate peptides. The addition of inorganic iron to food can cause changes in its physical, chemical, and sensory properties. For example, the addition of ferrous sulfate to infant cereals and tortillas can produce unacceptable color changes and a metallic taste. Organic iron supplements are less irritating to the intestines, but due to their low iron content and poor solubility in the gastrointestinal environment, they are not very effective in promoting iron bioavailability. Amino acid iron chelates such as ferrous glycine can significantly improve intestinal absorption of iron compared to ferrous sulfate, but due to their high price and the tendency to cause color reactions and lipid oxidation, they have gradually been replaced.

[0005] Iron supplements in the form of peptide iron chelates have a good effect on promoting iron bioavailability and can effectively solve the problem of iron deficiency. This is because peptide iron chelates still have advantages such as high solubility in the intestine, good stability and high safety. For example, Miao et al. (see literature DOI:10.1039 / c8fo02414f) isolated iron chelate peptides from bovine casein, but currently there is still little research on iron chelate peptides.

[0006] Therefore, more iron chelating peptides need to be developed to meet the current demand for iron supplementation in nutritional supplementation, disease treatment, etc. Summary of the Invention

[0007] The primary purpose of the present invention is to overcome the current problem of the lack of iron chelating peptides and provide a milk-derived phosphorylated peptide with the activity of enhancing intestinal iron absorption.2+ It has specific binding, strong iron chelation ability, and can significantly increase the amount of iron transport in the Caco-2 small intestinal epithelial cell model, thus having good activity in enhancing intestinal iron absorption and can be widely used in the fields of medicine, health products or food.

[0008] A further object of the present invention is to provide a use of the milk-derived phosphorylated peptide in the preparation of an iron supplement.

[0009] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0010] A milk-derived phosphorylated peptide having the activity of enhancing intestinal iron absorption, wherein the milk-derived phosphorylated peptide has a sequence as shown in SEQ ID NO: 1, and the glutamic acid at the amino terminal of the sequence is connected to 1 to 3 phosphoserines.

[0011] The inventors of the present invention have extracted a milk-derived phosphorylated peptide from β-casein that enhances intestinal iron absorption. Its sequence is EESITRINKKIE, and the amino-terminal glutamic acid in the sequence is linked to 1 to 3 phosphoserines. The structural formula of phosphoserine (represented by Sp) is shown below:

[0012] Phosphoserine forms peptides through dehydration condensation reactions between its amino and carboxyl groups and other amino acids.

[0013] The inventors of the present invention have found that the milk-derived phosphorylated peptide of the present invention can bind to Fe 2+ It has specific binding, strong iron chelation ability, and can significantly increase the amount of iron transport in the Caco-2 small intestinal epithelial cell model, thus having good activity in enhancing intestinal iron absorption and can be widely used in the fields of medicine, health products or food.

[0014] Preferably, the glutamic acid at the amino terminal of the sequence is connected to 1 or 3 phosphoserines, that is, the milk-derived phosphorylated peptide is SpEESITRINKKIE or SpSpSpEESITRINKKIE.

[0015] More preferably, the amino-terminal glutamic acid of the sequence is connected to three phosphoserines. Studies have shown that SpSpSpEESITRINKKIE has stronger iron chelating ability and better activity in improving intestinal iron absorption.

[0016] The milk-derived phosphorylated peptide of the present invention can be obtained by enzymatically hydrolyzing and separating β-casein, or by solid-phase synthesis.

[0017] The present invention also protects the use of the milk-derived phosphorylated peptide in preparing an iron supplement.

[0018] Preferably, the iron supplement is a medicine.

[0019] More preferably, the drug is a drug for preventing and / or treating iron deficiency anemia, or a drug for preventing and / or treating nervous system diseases.

[0020] More preferably, the drug is an oral preparation.

[0021] Preferably, the iron supplement is a health product.

[0022] More preferably, the health care product is a health care product for improving nutritional anemia.

[0023] More preferably, the health product is a nutritional supplement for supplementing minerals.

[0024] Preferably, the iron supplement is a food.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention provides a milk-derived phosphorylated peptide with the ability to enhance intestinal iron absorption. 2+ It has specific binding, strong iron chelation ability, and can significantly increase the amount of iron transport in the Caco-2 small intestinal epithelial cell model, thus having good activity in enhancing intestinal iron absorption and can be widely used in the fields of medicine, health products or food. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a graph showing the ferrous ion chelation rates of the β-casein hydrolysate and ultrafiltration fraction in Example 1.

[0028] Figure 2 This is a result diagram of the ferrous ion chelation rate of each separated component after one separation in Example 1.

[0029] Figure 3 This is a result diagram of the ferrous ion chelation rate of each separated component after the secondary separation in Example 1.

[0030] Figure 4 Milk-derived phosphorylated peptide and Fe 2+ 3D visualization of docking. Figure 4 A in the formula is SpEESITRINKKIE and Fe 2+ 3D visualization of the docking; Figure 4 B in the equation is SpSpSpEESITRINKKIE and Fe 2+ 3D visualization of the docking.

[0031] Figure 5 Graph showing the iron chelation rates of SpEESITRINKKIE and SpSpSpEESITRINKKIE of the present invention.

[0032] Figure 6 Graph showing the results of cytotoxicity assays of the Mw < 10 kDa fraction, SpEESITRINKKIE, and SpSpSpEESITRINKKIE.

[0033] Figure 7 The graph shows the results of the iron transport activity of the Mw < 10 kDa component, SpEESITRINKKIE, and SpSpSpEESITRINKKIE. DETAILED DESCRIPTION

[0034] In order to more clearly and completely describe the technical solution of the present invention, the present invention is further described in detail through specific embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Various changes can be made within the scope of the rights of the present invention.

[0035] The ferrous ion chelating activity of the samples of Example 1 and Example 3 was determined as follows:

[0036] The sample was dissolved in 50mM sodium acetate buffer at pH 5 at 1mg / mL. 250μL of the above solution was added to a 96-well plate, preheated at 37°C in a thermostatic shaker, taken out after 10 minutes, and 20μL of 0.25mM FeSO4·7H2O was added. After shaking and mixing, the timer was started. After 50 minutes (37°C), 15μL of 2.5mM ferroxine solution was added to terminate the reaction. After 10 minutes, the absorbance was measured at 562nm using an enzyme reader. Deionized water was used as the control group, and three parallels were used for each sample. The formula for calculating the chelation rate of ferrous ions is as follows:

[0037] (1) Ferrous ion chelation rate (%) = (Abs 对照 -Abs 样品 ) / Abs 对照 ×100%, where Abs 对照 is the absorbance value of the control group sample, Abs 样品 is the absorbance value of the sample;

[0038] (2) The ability of 1g sample to chelate ferrous ions (mg / g) = 1.116 × chelation rate (mg / g), where the reaction system contains 0.25mg of sample, 0.279 × 10 -3 mg of ferrous ions, if the chelation rate is a, that is, 0.25 mg of sample can chelate (0.279×10 -3 ×a) mg of ferrous ions, that is, 1 g of sample can combine with (1.116×a) mg of ferrous ions.

[0039] Example 1 Enzymatic Hydrolysis, Separation and Peptide Identification of β-Casein

[0040] 1.1 Enzymatic hydrolysis of β-casein

[0041] Take a certain amount of β-casein, add distilled water with a pH of 10.0 to a substrate concentration of 10%, and heat to dissolve in a 50°C water bath. After the β-casein is completely dissolved, adjust the pH to 7.30 with 1 mol / L NaOH or HCl. Add bromelain at an enzyme-to-substrate ratio of 0.31:100 and perform enzymatic hydrolysis at 55°C for 4.10 hours. After the enzymatic hydrolysis is completed, heat to inactivate the enzyme (95°C, 10 minutes), cool to room temperature, adjust the solution pH to an isoelectric point of 4.6 with 2 mol / L HCl, let it stand for 20 minutes, centrifuge (4000 rpm, 10 minutes), collect the supernatant, and freeze-dry to obtain the β-casein hydrolyzate.

[0042] 1.2 Separation of β-casein hydrolysate

[0043] The β-casein hydrolysate was separated using an ultrafiltration membrane with a molecular weight of 10 kDa to obtain two ultrafiltration fractions with Mw < 10 kDa and Mw ≥ 10 kDa, which were freeze-dried separately.

[0044] The ferrous ion chelating activity of the β-casein hydrolysate and the two ultrafiltration fractions was determined. Figure 1 As shown (different letters indicate significant differences, p < 0.05). Figure 1 It can be seen that the ferrous ion chelation rate of the component with Mw < 10 kDa is the highest, reaching 34.15±0.46%.

[0045] 1.3 Separation of Mw<10kDa components

[0046] Primary separation: Ultrafiltration yielded fractions with Mw <10 kDa, filtered through a 0.45 μm filter membrane, and separated by preparative liquid chromatography using a reverse-phase C18 glass column (20 μm, 15 mm × 460 mm). Chromatographic conditions were as follows: mobile phase A: deionized water containing 0.1% trifluoroacetic acid (TFA); mobile phase B: methanol containing 0.1% TFA; elution gradient: 0-10 min, 10%-20% mobile phase B; 10-30 min, 20%-35% mobile phase B; 30-80 min, 35%-60% mobile phase B; 80-100 min, 60%-70% mobile phase B; 100-120 min, 95%-95% mobile phase B; injection volume: 4 mL; flow rate: 10.0 mL / min; detection wavelengths: 214 nm and 280 nm, respectively. The eluted peaks were collected and concentrated to obtain 8 separated components, which were named F1, F2, F3, F4, F5, F6, F7, and F8, and freeze-dried.

[0047] The ferrous ion chelation activity of the 8 separated components was determined. Figure 2 As shown (different letters indicate significant differences, p < 0.05). Figure 2 It can be seen that the ferrous ion chelating activity of F4 component is significantly higher than that of other components. 2+ The chelation rate was 39.35±0.29%, Fe 2+ The chelating capacity was 43.92±0.32 mg / g.

[0048] Secondary separation: Fraction F4 was filtered through a 0.45 μm filter and further separated by preparative liquid chromatography using a Shimadzu PRC-ODS(K) steel column (5 μm, 4.6 mm × 200 mm). Chromatographic conditions were as follows: mobile phase A: deionized water containing 0.1% trifluoroacetic acid (TFA); mobile phase B: methanol containing 0.1% TFA; elution gradient: 10%-40% mobile phase B from 0 to 35 min; 40%-45% mobile phase B from 35 to 55 min; 45%-50% mobile phase B from 55 to 65 min; 95%-95% mobile phase B from 65 to 85 min; injection volume: 600 μL; flow rate: 5.0 mL / min; dual detection wavelengths: 214 nm and 280 nm. The eluted peaks were collected and concentrated to yield six fractions, designated M1, M2, M3, M4, M5, and M6, which were then freeze-dried.

[0049] The ferrous ion chelation activity of the six components was determined, and the results were as follows: Figure 3 As shown (different letters indicate significant differences, p < 0.05). Figure 3 It can be seen that the M4 component showed the strongest ferrous ion chelating activity, and its Fe 2+ The chelation rate was 90.91±0.1%, Fe 2+ The chelating capacity is 101.45±0.11 mg / g.

[0050] 1.4 HPLC-MS / MS identification of highly active iron-chelating peptides

[0051] 1 mg of the M4 fraction was placed in a centrifuge tube and deionized water was added to prepare a 1 mg / mL sample solution. The sample solution was desalted using a C18 desalting column, lyophilized, reconstituted with 0.1% formic acid, and centrifuged at 2000 × g for 8 min at 4°C. The supernatant was transferred to a vial and loaded for online LC-MS / MS analysis. Highly active iron-chelating peptides were identified using an LTQ-Orbitrap Velos Pro ETD mass spectrometer connected to a Thermo Easy-nLC liquid chromatography system. The sample injection volume was 12 μL, and the C18 analytical column (50 μm × 2 μm × 15 cm) was used at a column flow rate of 300 nL / min, a column temperature of 30°C, an ion transfer tube temperature of 300°C, and an S-Lens RF level of 60%. Mobile phase: Phase A was 0.1% formic acid in water, and phase B was 0.1% formic acid in acetonitrile. LC elution gradient: 0-70 min, 5%-35% mobile phase B; 70-77 min, 35%-100% mobile phase B; 77-82 min, 100%-100% mobile phase B. Mass spectrometry parameters were set as follows: (1) MS: scan range (m / z): 350-2000; resolution: 60,000; AGC target: 1e6; maximum injection time: 100 ms. (2) CID-MS / MS (full): iso.width (m / z): 1.0; collision energy: 35; dynamic exclusion time: 10 s.

[0052] The database search software used was Proteome Discoverer™ Software 2.5. The raw file was submitted to the Proteome Discoverer server, and the protein database established on Uniprot was selected for database search. The search parameters were set as follows: Protein Database: Bos taurus (Bovine) casein.fasta; Dynamic Modification: Phospho / +79.966 Da (S); Enzyme Name: No-Enzyme (no specific); Max. Missed Cleavage Sites: 2; Precursor Mass Tolorance: 10 ppm; Fragment Mass Tolorance: 0.6 Da.

[0053] A total of 232 peptides derived from enzymatically hydrolyzed β-casein were identified in the M4 fraction, with molecular weights ranging from 712.38 to 3320.52 Da and peptide chain lengths ranging from 6 to 27 amino acids. Of these, 99% were peptides with molecular weights below 3 kDa, and 94.4% were peptides less than 20 amino acids long.

[0054] Example 2 Molecular docking

[0055] A new ferrous ion model was created using Discovery Studio Client 2019. Hydrogenation and energy minimization were performed using the Protein Preparation tool. The binding energy of the interaction was predicted using the Calculate Docking Binding Energy option in the Docking module. Based on the docking binding energy, highly active β-casein iron chelate peptides were selected for stable chelation with ferrous ions.

[0056] The 232 peptides were ranked according to their molecular docking binding energy, and 71 peptides were found to be closely related to Fe 2+ The binding energy is lower than 0, indicating that it can bind to Fe 2+ Free binding occurs. 2+ The two milk-derived phosphorylated peptides SpEESITRINKKIE and SpSpSpEESITRINKKIE were bound stably, both of which contained key structures of phosphoserine residues and glutamic acid residues. The identification results of the two milk-derived phosphorylated peptides and their peptide characteristics are shown in Table 1.

[0057] Table 1 Identification results and peptide characteristics of milk-derived phosphorylated peptides

[0058]

[0059] SpEESITRINKKIE and SpSpSpEESITRINKKIE with Fe 2+ Theoretical combination model such as Figure 4 The carbonyl oxygen atom and hydroxyl oxygen atom of the carboxyl group in the third amino acid residue (glutamic acid residue) of the SpEESITRINKKIE sequence interact with Fe through metal receptor interaction and charge-charge interaction, respectively. 2+ The bond lengths of Fe-O bonds in the obtained SpEESITRINKKIE-Fe complexes are and The oxygen atom of the first phosphoserine residue in the SpSpSpEESITRINKKIE sequence binds to Fe via charge-charge interaction. 2+ The specific binding, the bond length of the Fe-O bond in the obtained SpSpSpEESITRINKKIE-Fe complex is The Fe-O bond lengths in the SpEESITRINKKIE-Fe complex and the SpSpSpEESITRINKKIE-Fe complex are both longer than those in Fe(IV) oxide. This indicates that the structures of both the SpEESITRINKKIE-Fe complex and the SpSpSpEESITRINKKIE-Fe complex are relatively stable.

[0060] Example 3 Determination of Iron Chelating Activity and Cytotoxicity of Milk-Derived Phosphorylated Peptides

[0061] 3.1 Verification of iron chelation activity

[0062] The milk-derived phosphorylated peptides SpEESITRINKKIE and SpSpSpEESITRINKKIE obtained above were synthesized by Nanjing Jiepeptide Biotechnology Co., Ltd. using solid phase synthesis. The purity of both peptides was greater than 98%, and then the chelating activity of ferrous ions was determined. Figure 5 As shown (** is highly significant, p < 0.01). The iron chelation rates of SpEESITRINKKIE and SpSpSpEESITRINKKIE were 87.18±0.89% and 91.15±0.31%, respectively (the iron chelation rates of both are higher than those of some existing iron chelating peptides, for example, the iron chelation rate of AVPYPQR is 59.76% (see document DOI:10.1039 / c8fo02414f) and the iron chelation rate of GPAGPHGPPGKDGR is 58.1% (see document DOI:10.1016 / j.jff.2017.06.013)), which are converted into iron chelation abilities of 97.30±1.00 mg / g and 101.72±0.34 mg / g, respectively. Both showed good iron chelation abilities; among them, SpSpSpEESITRINKKIE had stronger iron chelation ability than SpEESITRINKKIE.

[0063] 3.2 MTT assay for cytotoxicity

[0064] Caco-2 cells were purchased from the American Type Culture Collection (Rockville, MD, USA). Cells at passages 30-35 were used in subsequent experiments. Complete cell culture medium consisted of 79% EMEM basal medium, 20% fetal bovine serum, and 1% antibiotics (penicillin and streptomycin). The culture environment was maintained at 37°C, 5% CO₂, and 95% relative humidity, with complete cell culture medium replaced every two days.

[0065] The cells were seeded into T25 culture flasks. When the cell density reached 70%-80%, 0.25% EDTA-trypsin was added and digested at 37℃ for 3 minutes. The cells were passaged at a ratio of 1:3. Caco-2 cells in the logarithmic growth phase were cultured at a rate of 5×10 4 Cells were plated into 96-well plates at a density of 100 μL / well and incubated in complete culture medium for 24 hours to allow complete attachment. The cell culture medium was then removed, and 100 μL of sample solutions (dissolved in cell culture medium) of the Mw <10 kDa fraction, SpEESITRINKKIE, and SpSpSpEESITRINKKIE at varying concentrations (100, 250, 500, and 1000 μg / mL) were added to the experimental group, with eight wells added for each concentration. Cell culture medium was used as the blank control group, and the cells were placed in an incubator for 24 hours. The sample solution was removed, and 100 μL of 0.5 mg / mL MTT solution was added and incubated for 4 hours. Finally, the MTT solution was removed, and 100 μL of DMSO was added to dissolve the purple crystalline product. The absorbance was measured at 490 nm using a multi-functional microplate reader. Cell viability was calculated as follows: Cell viability (%) = (absorbance of experimental group / absorbance of blank control) × 100%.

[0066] Cytotoxicity test results Figure 6 As shown in the figure, the survival rate of Caco-2 cells after 24 hours of treatment was above 90%, indicating that all samples had no toxic effect on cells within this concentration range. Therefore, the subsequent iron transport activity experiments were carried out within this concentration range.

[0067] Example 4 Determination of Iron Transport Activity of Milk-Derived Phosphorylated Peptides

[0068] Establishment of Caco-2 monolayer cell model: Caco-2 cells of passage 30-35 were selected to establish a small intestinal epithelial monolayer cell model. Before inoculation, 0.5 mL of complete culture medium was added to the upper chamber of a 12-well polyester Transwell membrane culture plate (PET, Corning, 3460) and 1.5 mL of complete culture medium was added to the lower chamber. The plates were placed in an incubator for 1 hour to allow them to equilibrate to improve cell attachment efficiency. After 1 hour, the complete culture medium in the upper chamber was removed. When the cells grew to 80% of the T25 culture flask, 2 × 10 5 Cells were seeded into the upper chamber of a 12-well polyester Transwell culture plate at a density of 100 cells / mL (0.5 mL of cell suspension was added to the upper chamber). Culture was continued for 21 days, with the medium changed every other day until the cells formed a complete membrane (at the third week, the concentration of fetal bovine serum in the complete culture medium was increased to 25%). The integrity of the cell monolayer was assessed by measuring the transmembrane electrical resistance (TEER). When the transmembrane resistance was 500-1000 Ω / cm 2 At this time, the Caco-2 cell monolayer model was successfully established and can be used for transport experiments.

[0069] Before the start of the transport experiment, a new 12-well plate was prepared and 1.5 mL of complete medium was added to transfer the 21-day-old Caco-2 monolayer membrane to the new 12-well plate. The prepared FeCl2.4H2O solution, Mw<10 kDa component and FeCl2.4H2O premixed solution (Fe 2+ concentration of 80 μg / mL, concentration of Mw<10 kDa component was 568 μg / mL), SpEESITRINKKIE and FeCl2.4H2O premixed solution (Fe 2+ concentration of 80 μg / mL, concentration of SpEESITRINKKIE was 568 μg / mL) and SpSpSp EESITRINKKIE and FeCl2.4H2O premixed solution (Fe 2+ concentration of 80 μg / mL, concentration of SpSpSpEESI TRINKKIE was 568 μg / mL) were incubated in a 37 °C incubator for 1 h. The sample solution (0.5 mL) was added to the upper chamber of the Transwell nest plate, and the control group was added with FeCl2.4H2O solution. After the start of the transport, 1 mL of medium was taken from the lower chamber of the Transwell nest plate at 30, 60, 120, 180 min, respectively, and 1 mL of medium was quickly supplemented to maintain the volume of the transport system. The iron concentration of the lower chamber medium at each time point was determined by flame atomic absorption method. The iron transport amount at each time point was calculated according to the following formula:

[0070]

[0071] In the formula, T n is the total iron transport amount (μg) at each time point; 1.5 is the volume of the lower complete medium (mL); C n is the iron concentration (μg / mL) in the sample taken at different time points; 2.64 is the concentration of self-iron in the complete medium (μg / mL); 1 is the volume of the sample taken from the lower layer (mL); n is the independent table quantity, which can be 1, 2, 3, 4, representing 4 different time points, 30 min, 60 min, 120 min, and 180 min, respectively.

[0072] The results of the iron transport test are as follows: Figure 7As shown (different letters indicate significant differences, p < 0.05), at 30 minutes, the iron transport capacity of the Mw < 10 kDa component, SpEESITRINKKIE, and SpSpSpEESITRINKKIE increased by 74 ± 3%, 79 ± 1%, and 129 ± 2%, respectively, compared to the control group with FeCl2.4H2O. This indicates that the milk-derived phosphorylated peptide of the present invention promotes intestinal iron absorption and significantly increases the bioavailability of iron in Caco-2 cells. As time goes by, the iron transport capacity of SpSpSpEESITRINKKIE is always higher than that of SpEESITRINKKIE, showing a stronger effect in promoting iron absorption.

[0073] Through Examples 1 to 4, it is shown that the milk-derived phosphorylated peptide of the present invention can bind to Fe 2+ It has specific binding, strong iron chelating ability, and can significantly increase the amount of iron transport in the Caco-2 small intestinal epithelial cell model, thus having good activity in enhancing intestinal iron absorption.

[0074] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A milk-derived phosphorylated peptide having the activity of enhancing intestinal iron absorption, characterized in that: The milk-derived phosphorylated peptide is a peptide having glutamic acid at the amino end of the sequence shown in SEQ ID NO: 1 connected to 1 to 3 phosphoserine residues.

2. The milk-derived phosphorylated peptide according to claim 1, characterized in that: The amino-terminal glutamic acid of the sequence is linked to one or three phosphoserines.

3. Use of the milk-derived phosphorylated peptide according to claim 1 or 2 in the preparation of an iron supplement.

4. The use according to claim 3, characterized in that The iron supplement is a medicine.

5. The use according to claim 4, characterized in that The medicine is a medicine for preventing and / or treating iron deficiency anemia.

6. The use according to claim 4, characterized in that The medicine is an oral preparation.

7. The use according to claim 3, characterized in that The iron supplement is a health product, and the health product is a health product for improving iron deficiency anemia.

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