Mineral-binding milk proteins and peptides; occurrence, biochemical and technological characteristics

Minerals and trace elements in cow's milk occur as inorganic ions and salts or form complexes with proteins and peptides, carbohydrates, fats and small molecules. The main mineral binder or chelators of calcium are the caseins, αs1-casein, αs2-casein, β-casein and κ-casein, but also whey proteins and lactoferrin bind specific minerals like calcium, magnesium, zinc, iron, sodium and potassium. Less documented is the binding of trace elements. Peptides obtained byin vitroorin vivohydrolysis act as mineral trappers through specific and non-specific binding sites. They may then function as carriers, chelators, of various minerals and thus enhance or inhibit bioavailability. Peptides from milk proteins have found interesting new applications in the food industry as products with improved functionality or as ingredients of dietary products, or used in pharmaceutical industry. Fortification of foods with minerals in a low concentration has for a long time been used in some countries to overcome mineral deficiency, which is an increasing problem in humans. These types of foods are being used to create a new generation of super foods in the industry today.

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Are Faba Bean and Pea Proteins Potential Whey Protein Substitutes in Infant Formulas? An In Vitro Dynamic Digestion Approach

Foods ◽

10.3390/foods9030362 ◽

2020 ◽

Vol 9 (3) ◽

pp. 362

Author(s):

Linda Le Roux ◽

Olivia Ménard ◽

Raphaël Chacon ◽

Didier Dupont ◽

Romain Jeantet ◽

...

Keyword(s):

Faba Bean ◽

Whey Proteins ◽

Milk Proteins ◽

Protein Digestibility ◽

Cow Milk ◽

Partial Substitution ◽

Infant Formulas ◽

Pea Proteins

Infant formulas (IFs) are used as substitutes for human milk and are mostly based on cow milk proteins. For sustainability reasons, animal protein alternatives in food are increasingly being considered, as plant proteins offer interesting nutritional and functional benefits for the development of innovative IFs. This study aimed to assess how a partial substitution (50%) of dairy proteins with faba bean and pea proteins influenced the digestibility of IFs under simulated dynamic in vitro digestion, which were set up to mimic infant digestion. Pea- and faba bean-based IFs (PIF and FIF, respectively) have led to a faster aggregation than the reference milk-based IF (RIF) in the gastric compartment; that did not affect the digesta microstructure at the end of digestion. The extent of proteolysis was estimated via the hydrolysis degree, which was the highest for FIF (73%) and the lowest for RIF (50%). Finally, it was apparent that in vitro protein digestibility and protein digestibility-corrected amino acid score (PDCAAS)-like scores were similar for RIF and FIF (90% digestibility; 75% PDCAAS), but lower for PIF (75%; 67%). Therefore, this study confirms that faba bean proteins could be a good candidate for partial substitution of whey proteins in IFs from a nutritional point of view, provided that these in vitro results are confirmed in vivo.

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Atrial natriuretic factor binding sites in the jejunum

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1989.256.2.g436 ◽

1989 ◽

Vol 256 (2) ◽

pp. G436-G441 ◽

Cited By ~ 1

Author(s):

C. Bianchi ◽

G. Thibault ◽

A. De Lean ◽

J. Genest ◽

M. Cantin

Keyword(s):

Binding Sites ◽

Atrial Natriuretic Factor ◽

Specific Binding ◽

Rat Tissues ◽

Rat Jejunum ◽

Specific Binding Sites ◽

Natriuretic Factor ◽

Atrial Natriuretic

We have studied the localization and the characterization of atrial natriuretic factor (ANF) binding sites by radioautographic techniques. Quantitative in vitro radioautography with a computerized microdensitometer demonstrated the presence of high-affinity, low-capacity 125I-ANF-(99-126) binding sites (Kd, 48 pM; Bmax, 63 fmol/mg protein) mainly in the villi of 20-microns slide-mounted transverse sections of the rat jejunum. Competition curves showed 50% inhibitory concentrations of 55 and 1,560 pM for ANF-(99-126) and ANF-(103-123), respectively. In vivo electron microscope radioautography showed that 80% of the silver grains were localized on the lamina propria fibroblast-like cells, 18% on mature enterocytes, and 2% on capillaries. Bradykinin and adrenocorticotropin did not compete with ANF binding. These results demonstrate that ANF binding sites in the rat jejunum possess the pharmacological characteristics of functional ANF receptors encountered in other rat tissues, and ultrastructural radioautographs show their cellular distribution. Taken together, these results demonstrate the presence and the localization of specific binding sites for ANF in the jejunal villi of the rat small intestine.

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Comparison of immunomodulatory properties of purified lactoferrin, lactoperoxidase and β-casein in sheep

Journal of Dairy Research ◽

10.1017/s0022029998003112 ◽

1998 ◽

Vol 65 (4) ◽

pp. 697-701 ◽

Cited By ~ 5

Author(s):

CHUN W. WONG ◽

DENNIS L. WATSON ◽

GEOFFREY O. REGESTER ◽

GEOFFREY W. SMITHERS

Keyword(s):

Biomedical Applications ◽

Bovine Milk ◽

Milk Proteins ◽

Biologically Active ◽

Immunological Effects ◽

Bovine Milk Proteins ◽

Proteins And Peptides

Bovine milk contains a variety of proteins and peptides that are biologically active (Ogra & Ogra, 1978; Duncan & McArthur, 1981; Newby et al. 1982; Juto, 1985; Stoeck et al. 1989; Mincheva-Nilsson et al. 1990; Watson, 1990; Barta et al. 1991; Politis et al. 1991; Fiat et al. 1993). Our laboratory has a long-term interest in some purified milk proteins, particularly lactoferrin (LF), lactoperoxidase (LP) and β-casein (β-CN), which have been shown to be immunologically significant. Some of our recent studies on these bovine milk proteins, particularly β-CN, indicated that their in vitro immunological effects did not always parallel their in vivo activities (Wong et al. 1996a, b; 1997a, b). This study was designed to investigate and compare the capacity of these purified bovine milk proteins to modulate a range of components that are vital to in vivo immune responses in sheep, with a view to providing further information on their potential in biomedical applications. To achieve this objective, a sensitive lymphatic cannulation model was employed that allows in vivo immune components and their functions to be measured in lymph collected under physiological conditions.

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Kinetic analysis of rat parotid gland muscarinic receptors in vivo: comparison with brain and heart

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1993.264.3.g541 ◽

1993 ◽

Vol 264 (3) ◽

pp. G541-G552

Author(s):

Y. Hiramatsu ◽

R. Kawai ◽

R. C. Reba ◽

T. R. Simon ◽

B. J. Baum ◽

...

Keyword(s):

Parotid Gland ◽

Plasma Membranes ◽

Specific Binding ◽

Muscarinic Acetylcholine Receptor ◽

Binding Potential ◽

Specific Binding Sites ◽

Rat Parotid Gland ◽

Rat Parotid

(RR)- and (SS)-quinuclidinyl iodobenzilate enantiomers [(RR)- and (SS)-IQNB, active and inert, respectively] have been synthesized for quantitative evaluation of muscarinic acetylcholine receptor (mAChR) binding. Pharmacokinetic approaches have not been used previously to assess in vivo IQNB binding in nonexcitable tissues. We have applied this method to examine mAChRs in rat parotid gland in comparison to those in brain and heart. Short-term infusion studies in vivo showed that the "instantaneous" reversible binding of (RR)- and (SS)-IQNB was high in the parotid (greater nonspecific binding potential), intermediate in the heart, and lowest in cortex and cerebellum. Long-term bolus injection experiments showed that the parotid gland mAChRs possessed a binding potential for receptor specific sites (380), which was intermediate between that of parietal cortex (930) and cerebellum (10) and greater than that of heart (165). In vitro binding to plasma membranes was generally consistent with the in vivo findings. In aggregate, these studies show that mAChRs can be evaluated in vivo in a nonexcitable tissue with the use of stereospecific ligands and a pharmacokinetic approach. The data suggest that IQNB, a mAChR antagonist, can identify characteristics of specific binding sites, which may reflect tissue differences.

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A quantitative binding model for the Apl protein, the dual purpose recombination-directionality factor and lysis-lysogeny regulator of bacteriophage 186

Nucleic Acids Research ◽

10.1093/nar/gkaa655 ◽

2020 ◽

Vol 48 (16) ◽

pp. 8914-8926

Author(s):

Erin E Cutts ◽

J Barry Egan ◽

Ian B Dodd ◽

Keith E Shearwin

Keyword(s):

Binding Sites ◽

Specific Binding ◽

Attachment Site ◽

Binding Energies ◽

Sequence Specificity ◽

Binding Studies ◽

Binding Model ◽

Specific Binding Sites

Abstract The Apl protein of bacteriophage 186 functions both as an excisionase and as a transcriptional regulator; binding to the phage attachment site (att), and also between the major early phage promoters (pR-pL). Like other recombination directionality factors (RDFs), Apl binding sites are direct repeats spaced one DNA helix turn apart. Here, we use in vitro binding studies with purified Apl and pR-pL DNA to show that Apl binds to multiple sites with high cooperativity, bends the DNA and spreads from specific binding sites into adjacent non-specific DNA; features that are shared with other RDFs. By analysing Apl's repression of pR and pL, and the effect of operator mutants in vivo with a simple mathematical model, we were able to extract estimates of binding energies for single specific and non-specific sites and for Apl cooperativity, revealing that Apl monomers bind to DNA with low sequence specificity but with strong cooperativity between immediate neighbours. This model fit was then independently validated with in vitro data. The model we employed here is a simple but powerful tool that enabled better understanding of the balance between binding affinity and cooperativity required for RDF function. A modelling approach such as this is broadly applicable to other systems.

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Contribution of gangliosides to thyroxin binding with plasma membranes

Problems of Endocrinology ◽

10.14341/probl11370 ◽

1995 ◽

Vol 41 (2) ◽

pp. 28-30

Author(s):

T. S. Saatov ◽

F. Ya. Gulyamova ◽

G. U. Usmanova

Keyword(s):

Binding Sites ◽

Plasma Membranes ◽

Binding Capacity ◽

Specific Binding ◽

Brain Cell ◽

Cell Recognition ◽

High Affinity ◽

Specific Binding Sites

Besides intracellular receptors of thyroid hormones, specific binding sites for T3 and T4 were detected on plasma membranes (PM) of some cells and a relationship between membrane reception .and lipid composition of membranes shown. The parameters of 125I-T4 binding to highly purified PM of hepatic and cerebral cells of rats were studied. The hepatic and cerebral cellular membranes were found to contain two sites of hormone binding each, one of these sites being characterized by a high affinity and low capacity, and the other by low affinity and a higher binding capacity. The association constant of highly affine site of hepatocyte membranes was found to be higher than that of brain cell membranes. T4 membranous receptors may be significant in the process of cell “recognition" by the hormone. In vivo and in vitro experiments with 125I-T4 and 14C-labeled thyroxin in ganglioside fractions showed appreciable binding of the hormone to Gm3 fraction, this evidently pointing to participation of this, ganglioside in T4 interaction with membrane receptor. It is possible that gangliosides situated on membranous surface are components of or function as receptors.

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A quantitative binding model for the Apl protein, the dual purpose recombination-directionality factor and lysis-lysogeny regulator of bacteriophage 186

10.1101/784983 ◽

2019 ◽

Author(s):

Erin Cutts ◽

J. Barry Egan ◽

Ian Dodd ◽

Keith Shearwin

Keyword(s):

Binding Sites ◽

Specific Binding ◽

Attachment Site ◽

Binding Energies ◽

Sequence Specificity ◽

Binding Studies ◽

Binding Model ◽

Specific Binding Sites

AbstractThe Apl protein of bacteriophage 186 functions both as an excisionase and as a transcriptional regulator; binding to the phage attachment site (att), and also between the major early phage promoters (pR-pL). Like other recombination directionality factors (RDFs), Apl binding sites are direct repeats spaced one DNA helix turn apart. Here, we use in vitro binding studies with purified Apl and pR-pL DNA to show that Apl binds to multiple sites with high cooperativity, bends the DNA, and spreads from specific binding sites into adjacent non-specific DNA; features that are shared with other RDFs. By analysing Apl’s repression of pR and pL, and the effect of operator mutants in vivo with a simple mathematical model, we were able to extract estimates of binding energies for single specific and non-specific sites and for Apl cooperativity, revealing that Apl monomers bind to DNA with low sequence specificity but with strong cooperativity between immediate neighbours. This model fit was then independently validated with in vitro data. The model we employed here is a simple but powerful tool that enabled better understanding of the balance between binding affinity and cooperativity required for RDF function. A modelling approach such as this is broadly applicable to other systems.

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Autoradiographic determination of dexamethasone binding sites along the rabbit nephron

AJP Renal Physiology ◽

10.1152/ajprenal.1983.244.3.f325 ◽

1983 ◽

Vol 244 (3) ◽

pp. F325-F334 ◽

Cited By ~ 5

Author(s):

N. Farman ◽

A. Vandewalle ◽

J. P. Bonvalet

Keyword(s):

Proximal Tubule ◽

Binding Sites ◽

Specific Binding ◽

Rabbit Kidney ◽

Nuclear Binding ◽

Specific Binding Sites ◽

In Vitro Incubation ◽

Collecting Tubules

Specific binding sites of tritiated dexamethasone ([3H]dex) along the tubule of rabbit kidney were investigated using an autoradiographic method (dry film) on isolated tubular segments. After in vitro incubation of kidney pyramids with [3H]dex (0.15-53 nM) in the presence or absence of an excess (X200) of unlabeled dexamethasone, tubular segments were microdissected and processed for autoradiography. A quantitative analysis of specific labeling over cytoplasm and nuclei was performed. Specific nuclear binding was observed in all tubular segments beyond the pars recta. This binding was dose dependent and reached much higher values than those reported for aldosterone. In the proximal tubule, the specific labeling was also high but remained mostly cytoplasmic. The meaning of these drastically different intracellular localizations is still open to interpretation. Autoradiography was performed after in vivo injection of [3H]dex and [3H]aldosterone. The results were not different from those described here for dexamethasone and from those previously reported for aldosterone after in vitro incubation. We conclude that specific nuclear binding sites for dexamethasone range over the nephron except for proximal tubule, with no great difference among segments, in contrast to specific sites for aldosterone, which are restricted to distal and cortical collecting tubules. The exact significance of the proximal cytoplasmic specific binding of [3H]dex remains to be determined.

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Bioactive peptide derived from in vitro proteolysis of bovine β-lactoglobulin and its effect on smooth muscle

Journal of Dairy Research ◽

10.1017/s0022029996001926 ◽

1997 ◽

Vol 64 (1) ◽

pp. 149-155 ◽

Cited By ~ 23

Author(s):

ANNE PIHLANTO-LEPPÄLÄ ◽

ILARI PAAKKARI ◽

MERJA RINTA-KOSKI ◽

PIRKKO ANTILA

Keyword(s):

Guinea Pig ◽

Proteolytic Enzymes ◽

Whey Proteins ◽

Casein Hydrolysate ◽

Milk Proteins ◽

Biologically Active ◽

Guinea Pig Ileum ◽

Β Lactoglobulin

Milk proteins have largely been considered as providing essential amino acids, but oligopeptides derived from milk proteins have been shown to possess biological functions. In vitro, opioid activity was first reported in bovine β-casein hydrolysate by Brantl et al. (1979). Precursors of biologically active peptides have been demonstrated in vivo after digestion of milk (Scanff et al. 1992). Peptides that inhibit platelet aggregation (Fiat et al. 1989), stimulate the immune system (Migliore-Samour et al. 1989), inhibit angiotensin I converting enzyme (Maruyama & Suzuki, 1982) and are involved in intestinal Ca solubilization and absorption (Sato et al. 1986) have also been isolated from bovine casein hydrolysates.Bioactive peptides from whey proteins and their physiological effects have received less attention than those from casein. Peptides with opiate-like activity include the lactorphins, residues 50–53 in bovine and human α-lactalbumin and 102–105 in bovine β-lactoglobulin (β-lg) (Chiba & Yoshikawa, 1986; Yoshikawa et al. 1986; Antila et al. 1991). Yamauchi (1992) has reported that a peptide derived from β-lg induced contraction of guinea pig ileum longitudinal muscle in the absence of electric stimulation and agonist. The fragment, containing residues 146–149 of β-lg (His–Ile–Arg–Leu), was called β-lactotensin.The purpose of this study was to determine whether β-lactotensin was released from bovine β-lg by in vitro proteolysis using different proteolytic enzymes. The pharmacological activity of this tetrapeptide was characterized in guinea pig ileum in vitro using a synthetic fragment.

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Brain Specific Benzodiazepine Receptors

The British Journal of Psychiatry ◽

10.1192/bjp.133.3.249 ◽

1978 ◽

Vol 133 (3) ◽

pp. 249-260 ◽

Cited By ~ 167

Author(s):

Claus Bræstrup ◽

Richard F. Squires

Keyword(s):

Binding Sites ◽

Neuronal Degeneration ◽

Specific Binding ◽

Benzodiazepine Receptors ◽

Clinical Effects ◽

Single Class ◽

Specific Binding Sites ◽

Benzodiazepine Binding Sites

SummaryBrain membranes from rat and human contain a single class of brain specific binding sites for pharmacologically and clinically active benzodiazepines. There is good correlation between the pharmacological effects of benzodiazepines and the affinity for the 3H-diazepam binding site.Benzodiazepine binding sites are not present on glial cells. Selective neuronal degeneration experiments in rats indicate a neuronal localization. 3H-Flunitrazepam is a very suitable ligand for affinity binding and it binds to the same class of binding sites as 3H-diazepam.Our results indicate that the in vitro3H-diazepam and 3H-flunitrazepam binding sites are the receptors which in vivo mediate various pharmacological and clinical effects of benzodiazepines.

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