Piotr Minkiewicz

Food‐Originating ACE Inhibitors, Including Antihypertensive Peptides, as Preventive Food Components in Blood Pressure Reduction

This work is a literature overview on angiotensin-converting enzyme (ACE) inhibitory/antihypertensive peptides in food protein sources. The following aspects related to peptides with the above-mentioned bioactivity are discussed: (i) mechanism of action of ACE, (ii) the structural character of ACE inhibitors/antihypertensive peptide sequences determined by different methods, including quantitative structure-activity relationship studies, (iii) their food sources, (iv) absorption of peptides, (v) in vitro and in vivo approaches involved in the production and potential release of peptide ACE inhibitors as well as in silico methods applied in research concerning peptides.

Database of biologically active peptide sequences.

Proteins are sources of many peptides with diverse biological activity. Such peptides are considered as valuable components of foods with desired and designed biological activity. Two strategies are currently recommended for research in the area of biological activity of food protein fragments. The first strategy covers investigations on products of enzymic hydrolysis of proteins. The second one is synthesis of peptides identical with protein fragments and investigations using these peptides. It is possible to predict biological activity of protein fragments using sequence alignments between proteins and biologically active peptides from database. Our database contains currently 527 sequences of bioactive peptides with antihypertensive, opioid, immunomodulating and other activities. The sequence alignments can give information about localization of biologically active fragments in protein chain, but not about possibilities of enzymic release of such fragments. The information is thus equivalent with this obtained using synthetic peptides identical with protein fragments. Possibilities offered by the database are discussed using wheat alpha/beta-gliadin, bovine beta-lactoglobulin and bovine beta-casein (including influence of genetic polymorphism and genetic engineering on amino acid sequences) as examples.

Influence of glycosylation on micelle-stabilizing ability and biological properties of C-terminal fragments of cow's κ-casein

Abstract C-terminal fragment of bovine κ-casein contains glycosidic residues. There are several glycoforms of κ-casein containing different kinds and numbers of glycosidic residues. Such heterogeneity affects properties of this protein and its fragments. The C-terminal fragment of cows κ-casein (residues: 106–169) is the main factor stabilizing casein micelles. Glycosidic moieties connected to this fragment enhance the ability of κ-casein to stabilize micelles and also the resistance of this protein to the action of proteolytic enzymes and high temperature in simple model systems. κ-Casein, its C-terminal fragment (macropeptide or glycomacro-peptide) or products of its proteolysis can inhibit proliferation of lymphocytes B, binding Cholera toxin to its receptor, hemagglutination of influenza virus, adhesion of bacteria to cell surface, acid secretion in the stomach, as well as stimulate the release of cholecystokinin in the intestinal cells and the growth of Lactococcus lactis bacteria. Glycosidic moieties may act as an information carrier enabling recognition of compounds (e.g. components of cells) interacting with κ-casein, glycomacropeptide or its fragments.

Bovine Meat Proteins as Potential Precursors of Biologically Active Peptides - a Computational Study based on the BIOPEP Database

The aim of the present study was to perform an in silico evaluation of bovine meat proteins as potential precursors of biologically active peptides, as well as to determine whether such peptides can be released by selected proteolytic enzymes. The sequences of 19 bovine meat proteins were processed using the BIOPEP database and program. The profiles of potential biological activity of protein fragments were determined and the following parameters were calculated: the frequency of occurrence of fragments with given activity (A), the frequency of release of fragments with given activity by selected enzymes (AE), and the relative frequency of release of fragments with given activity by selected enzymes (W). Among the examined proteins, collagen and elastin appear to be the richest potential source of bioactive peptides, in particular of angiotensin-converting enzyme inhibitors, antithrombotic fragments, inhibitors of dipeptidyl peptidase IV and peptides regulating gastric mucosal activity. The high number of bioactive fragments in collagen and elastin is associated with a high content of glycine and proline, amino acids that are most abundant in biologically active fragments. Of the two investigated proteolytic enzymes, Proteinase K — an enzyme with broad specificity (e.g., against peptide bonds formed by the carboxyl groups of proline) can release considerably more biologically active fragments than Proteinase P1 — an enzyme with narrow specificity, not including proline residues.

Angiotensin I-Converting Enzyme (ACE) Inhibitory Activity and ACE Inhibitory Peptides of Salmon (Salmo salar) Protein Hydrolysates Obtained by Human and Porcine Gastrointestinal Enzymes

The objectives of the present study were two-fold: first, to detect whether salmon protein fractions possess angiotensin I-converting enzyme (ACE) inhibitory properties and whether salmon proteins can release ACE inhibitory peptides during a sequential in vitro hydrolysis (with commercial porcine enzymes) and ex vivo digestion (with human gastrointestinal enzymes). Secondly, to evaluate the ACE inhibitory activity of generated hydrolysates. A two-step ex vivo and in vitro model digestion was performed to simulate the human digestion process. Salmon proteins were degraded more efficiently by porcine enzymes than by human gastrointestinal juices and sarcoplasmic proteins were digested/hydrolyzed more easily than myofibrillar proteins. The ex vivo digested myofibrillar and sarcoplasmic duodenal samples showed IC50 values (concentration required to decrease the ACE activity by 50%) of 1.06 and 2.16 mg/mL, respectively. The in vitro hydrolyzed myofibrillar and sarcoplasmic samples showed IC50 values of 0.91 and 1.04 mg/mL, respectively. Based on the results of in silico studies, it was possible to identify 9 peptides of the ex vivo hydrolysates and 7 peptides of the in vitro hydrolysates of salmon proteins of 11 selected peptides. In both types of salmon hydrolysates, ACE-inhibitory peptides IW, IY, TVY and VW were identified. In the in vitro salmon protein hydrolysates an ACE-inhibitory peptides VPW and VY were also detected, while ACE-inhibitory peptides ALPHA, IVY and IWHHT were identified in the hydrolysates generated with ex vivo digestion. In our studies, we documented ACE inhibitory in vitro effects of salmon protein hydrolysates obtained by human and as well as porcine gastrointestinal enzymes.

The Preventive Potential of Milk and Colostrum Proteins and Protein Fragments

This study presents and analyzes the results of in silico, in vitro, and in vivo tests investigating the potential preventive properties of a group of biologically active milk and colostrum proteins and peptides; that is, casein, α-lactalbumin, β-lactoglobulin, lysozyme, lactoferrin, glycomacropeptide, proline-rich peptides, and lactoperoxidase. Casein or its peptides lowers blood pressure, reduces tumor growth, and shows anticoagulant, antimicrobial, and antioxidant activity. Casein hydrolysates decrease the probability of diabetes. α-Lactalbumin and β-lactoglobulin manifest antiviral activity directed against HIV and antibacterial and hypotensive activities. A diet rich in α-lactalbumin has antistress, antidepressive, and anticarcinogenic properties. Lysozyme is used as a supplement in infant formulas and an anti-inflammatory and analgesic agent in neoplastic diseases. Lactoferrin demonstrates an antibacterial, antiviral, fungistatic, antiparasitic, and antithrombotic effect. Glycomacropeptide is characterized by antibacterial, antiviral, and antithrombotic properties. Colostrinin, a proline-rich peptide, is applied in the treatment of neurodegenerative diseases of the brain and autoimmune diseases. Lactoperoxidase is an antimicrobial agent. Studies indicate that milk and colostrum proteins and peptides have many applications in the prevention and treatment of various diseases in patients from all age groups.

Computational Characterisation and Identification of Peptides for in silico Detection of Potentially Celiac-Toxic Proteins

This work reports on in silico analysis of celiac-toxic peptide occurrence in proteins. The toxic properties of celiac disease are linked to the presence of specific amino acid sequences and the properties of their environment. The analysed celiac-toxic peptides were found to be predominated by unordered structures of random coil and β-turns. Proline and glutamine-rich amino acid sequences from hydrophilic β-turns were exposed on the surface of the precursor proteins. The sequence motifs represented by gluten peptide epitopes or tetrapeptides with surroundings seem to represent an immunodominant structure. The application of MS BLAST software enabled identification of a few fragments with high degrees of identity to the toxic peptides in one protein sequence. Rich sources of celiac-disease-potentiating peptides were wheat gliadins, barley hordeins and rye secalins as well as low-molecular weight fractions of glutenin. In addition, amino acid sequences with a high degree of identity to the toxic peptides examined were detected in maize zein, oat avenin, protein of rice, yeast and chicken muscles, as well as β-casein and galanin.

BIOPEP database of sensory peptides and amino acids

Peptides and amino acids belong to compounds that influence the taste of foods. The aim of this study was to develop a database of sensory peptides and amino acids. Information about the taste of the analyzed compounds was obtained from sensory studies described in the literature. The database of sensory peptides and amino acids has identical structure to the BIOPEP database of biologically active peptides. The information about sensory peptides and amino acids was inserted into the database using standard BIOPEP layouts for bioactive peptides. Information about the biological activity of sensory peptides was obtained from BIOPEP and other databases. The information annotated in the BIOPEP database of sensory peptides and amino acids includes: sequence written in a one-letter code, information about taste, reference, structure written with the use of chemical codes (SMILES, InChI and InChIKey), bioactivity data (mainly inhibition of proteolytic enzymes), if applicable, and ID numbers from other biological and chemical databases. The database contains tools for determining the location of peptides in protein sequences (profiles of potential sensory activity), comparing protein sequences as precursors of sensory peptides based on the frequency of sensory fragments as a quantitative descriptor, simulating proteolysis and calculating novel parameters for quantitative description of simulated proteolysis. The BIOPEP database of sensory peptides and amino acids is available at http://www.uwm.edu.pl/biochemia/index.php/pl/biopep. It is an open access resource that does not require user registration.

Food protein-originating peptides as tastants - Physiological, technological, sensory, and bioinformatic approaches

Taste is one of the factors based on which the organism makes the selection of what to ingest. It also protects humans from ingesting toxic compounds and is one of the main attributes when thinking about food quality. Five basic taste sensations are recognized by humans: bitter, salty, sour, sweet, and umami. The taste of foods is affected by some molecules of some specific chemical nature. One of them are peptides derived from food proteins. Although they are not the major natural compounds originating from food sources that are responsible for the taste, they are in the area of scientific research due to the specific composition of amino acids which are well-known for their sensory properties. Literature data implicate that sweet, bitter, and umami are the tastes attributable to peptides. Moreover, the bitter peptide tastants are the dominant among the other tastes. Additionally, other biological activities like, e.g., inhibiting enzymes that regulate the body functions and acting as preventive food agents of civilization diseases, are also associated with the taste of peptides. The advance in information technologies has contributed to the elaboration of internet archives (databases) as well as in silico tools for the analysis of biological compounds. It also concerns peptides - namely taste carriers originating from foods. Thus, our paper provides a summary of knowledge about peptides as tastants with special attention paid to the following aspects: a) basis of taste perception, b) taste peptides detected in food protein sequences with special emphasis put on the role of bitter peptides, c) peptides that may enhance/suppress the taste of foods, d) databases as well as bioinformatic approaches suitable to study the taste of peptides, e) taste-taste interactions, f) basis of sensory analysis in the evaluation of the taste of molecules, including peptides, and g) the methodology applied to reduce/eliminate the undesired taste of peptides. The list of taste peptides serving some biological functions is presented in the Supplement file. The information provided includes database resources, whereas peptide sequences are given with InChiKeys, which is aimed at facilitating the Google® search. Our collection of data regarding taste peptides may be supportive for the scientists working with the set of peptide data in the context of structure-function activity of peptides.

Update of the List of Allergenic Proteins From Milk, Based on Local Amino Acid Sequence Identity with Known Epitopes From Bovine Milk Proteins - a Short Report

Update of the List of Allergenic Proteins From Milk, Based on Local Amino Acid Sequence Identity with Known Epitopes From Bovine Milk Proteins-a Short Report The study involved the screening of protein sequence database nrdb 95 for sequences containing fragments identical with experimentally proven sequential epitopes of bovine milk proteins. Such fragments were found in proteins from milk of the buffalo (Bubalus bubalis), yak (Bos grunniens), goat (Capra hircus) and ewe (Ovis aries). Some proteins, such as α-lactalbumins (from the yak, buffalo and goat) and κ-caseins (from the goat and ewe), have not been previously considered as allergens. They were entered into a new database of allergenic proteins from foods and their epitopes, which is part of the BIOPEP database http://www.uwm.edu.pl/biochemia. The proteins containing fragments identical with linear epitopes from known allergens should also be classified as allergens, based on local sequence identity. The absence of common linear epitopes with known allergens cannot be treated as the evidence that a given protein is not allergenic.