Кемерово, Кемеровская область, Россия
Results of biotechnological research on controlled hydrolysis of casein and production of peptide complexes are summarized in the present article. Selection of processing parameters and optimization of the conditions of enzymatic hydrolysis of milk proteins allowed for the development of a resource-efficient technology for the production of peptide complexes. Enzymatic hydrolysis of peptide bonds R1-CONH-R2 + H2O - R1COOH + NH2R2 was considered using the example of casein and a range of proteolytic enzymes (trypsin and chymotrypsin) belonging to the hydrolase class. Enzyme solution (0.1% m/v) was added to each protein solution so that the final enzyme-substrate ratio was 1:25, 1:50, or 1:100. The enzyme-substrate ratio of 1:50 was shown to be optimal, and the re-commended temperature and pH values were 50±1°С and 7.50±0.01, respectively. The degree of hydrolysis is one of the parameters characterizing the overall changes in the amino acid composition of proteins. Therefore, a time period of 12.00±0.05 h was chosen as the optimal duration of the hydrolysis process. Further research was focused on the analysis of peptide profiles using MALDI-TOF MS based on identification of peptide sequences. The studies have shown that casein hydrolysates are rich in biologically active peptide complexes. The detection of such complexes in hydrolysates of casein was the main result of the study. For example, the peptide β-casokinin (amino acid sequence Ala-Val-Pro-Tyr-Pro-Gln-Arg) is an inhibitor of angiotensin-converting enzyme.
casein, enzyme preparations, peptides, prevention, hypertensive disease, chronic cardiac insufficiency
INTRODUCTION
According to a report by the All-Russian Health-care Organization, the mortality from cardiovascular disease in Russia is the highest in the world. Deaths caused by cardiovascular diseases account for 57% of total mortality in Russia, with 1.3 million people dying from these diseases every year. Coronary heart disease and hypertension remain the most common diseases of the cardiovascular system. High blood pressure re-mains unnoticed very often due to the lack of clinical manifestations, and therefore it is a risk factor for the development of coronary heart disease, congestive heart failure, stroke, and disturbances of the function of kidneys and other organs [1].
The development of technology for the manufactu-ring of therapeutics and functional foods intended for the prevention of cardiovascular disease is of especial importance. Functional foods of plant and animal origin play an important role in the prevention of disease. Functional foods are systematically used in the form of special diets capable both of preventing disturbances of physiological functions and metabolic processes in the body and of improving human health due to the presence of essential nutrients. These food products play a considerable role in the prevention of various diseases. Proper nutrition including nutriceu-ticals and functional foods enhances immunity and defense capacity of the body and activates anabolic processes, having a general positive effect on health [2].
The development and implementation of food for persons who are prone to or suffering from hyper-tension is currently in progress in Russia. Notably, foods enriched in peptides, individual amino acids, or fatty acids, as well as dairy products obtained using selected strains of lactic acid bacteria, and other products of this type are entering the market of functional foods and dietary supplements [4]. At this, the interest towards the structure and function of low molecular weight peptides produced by controlled enzymatic hydrolysis of high-quality proteins fulfilling a range of specific biological functions in the body is increasing.
A large number of biologically active peptides that are either naturally present in food or formed during enzymatic or chemical (acid) hydrolysis of the dietary proteins was identified during the past decade. Natural processing of dietary protein in the digestive tract (and preceding fermentation in the case of pre-fermented foods) enables the release of these peptides from the proteins and their functioning as independent regulatory units with hormone-like activity. A consi-derable number of such peptides possessing a wide range of biological functions has been identified already [3, 4].
Raw materials of animal origin, namely, milk and dairy products, are among the sources of biologically active peptides. However, such peptides can be isolated from a variety of foods such as egg, fish, shellfish, grains (rice, wheat, buckwheat, barley, and maize), soybeans, and radishes. Functional proteins from milk have an exceptionally broad range of biological activity. Bioactive peptides can be formed from both casein (αs, β, k, and κ-casein) and whey proteins (lactoferrin and immunoglobulin, α-lactalbumin, and β-lactog-lobulin) [5]. Use of dietary products enriched with peptides derived from milk proteins and capable of blocking the conversion of the inactive peptide angiotensin I into the active compound angiotensin II is an efficient and safe way of lowering blood pressure. Nitric oxide activates the enzyme guanylate cyclase and promotes the formation of cyclic guanosine monophosphate, which has vasodilatory activity due to its effect on smooth muscle cells [1]. Supplementation of food with functional whey casoplatelins possessing an antithrombotic effect reduces the risk of complications in patients suffering from hypertension and hypercholesterolemia [7].
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