Bartłomiej Dziuba

Milk proteins-derived bioactive peptides in dairy products: molecular, biological and methodological aspects

Proteins are one of the primary components of the food, both in terms of nutrition and function. They are main source of amino acids, essential for synthesis of proteins, and also source of energy. Additionally, many proteins exhibit specific biological activities, which may have effect on functional or pro-health properties of food products. These proteins and their hydrolysis products, peptides, may influence the properties of food and human organism. The number of commercially available food products containing bioactive peptides is very low, apart from that milk proteins are their rich source. It could be supposed that number of available products with declared activity will rise in near future because of observed strong uptrend on interest in such products. Molecular and biological properties of milk proteins, as precursors of bioactive peptides was characterised in the work. Therefore, the strategy of research and obtaining of such peptides both in laboratory and industrial scale, as well as the range of their commercial application, was presented. Several examples of research efforts presenting high potential to develop new products containing bioactive peptides from milk proteins and predetermined as nutraceuticals was described.

New Milk Protein-Derived Peptides with Potential Antimicrobial Activity: An Approach Based on Bioinformatic Studies

New peptides with potential antimicrobial activity, encrypted in milk protein sequences, were searched for with the use of bioinformatic tools. The major milk proteins were hydrolyzed in silico by 28 enzymes. The obtained peptides were characterized by the following parameters: molecular weight, isoelectric point, composition and number of amino acid residues, net charge at pH 7.0, aliphatic index, instability index, Boman index, and GRAVY index, and compared with those calculated for known 416 antimicrobial peptides including 59 antimicrobial peptides (AMPs) from milk proteins listed in the BIOPEP database. A simple analysis of physico-chemical properties and the values of biological activity indicators were insufficient to select potentially antimicrobial peptides released in silico from milk proteins by proteolytic enzymes. The final selection was made based on the results of multidimensional statistical analysis such as support vector machines (SVM), random forest (RF), artificial neural networks (ANN) and discriminant analysis (DA) available in the Collection of Anti-Microbial Peptides (CAMP database). Eleven new peptides with potential antimicrobial activity were selected from all peptides released during in silico proteolysis of milk proteins.

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.