Modulation of physico-chemical properties of bovine β-casein by nonenzymatic glycation associated with enzymatic dephosphorylation

A major bovine casein fraction, β-casein was chemically glycated and/or enzymatically dephosphorylated. Ten glucose and nine lactose moieties were attached while all phosphate groups were removed. Glycation shifted the pI to acidic pH range and decreased the solubility at acidic pHs while dephosphorylation shifted the pI to neutral pH range and increased the solubility at acidic pHs. Dephosphorylation led to longer retention time measured using the reversed-phase high-performance liquid chromatography and affected UV-spectra of β-casein which suggested structural changes. Glycation did not affect these properties. Both modifications decreased the calcium sensitivity of β-casein, making it to keep αS1-casein in solution in the presence of Ca2+

Charakterystyka zmian wybranych wlasciwosci bialek bobiku pod wplywem przechowywania

The purpose of this work was to characterize some physico-chemical properties of proteins in raw and stored Tibo faba beans. The storage caused that the faba bean proteins were partialy degraded and hydrolyscd, which resulted in a decreased content of albumins, globulins, and amino acids in stored seeds. The nutritional value of proteins decreased due to lass of essencial amino acids and lower susceptibility of the proteins to proteolytic enzymes. Opposite to globulins, trypsin released more non-protein nitrogen from albumins than pepsin. The yield of extraction of albumins and globulins decreased upon storage and some modification in the protein conformations, most probably due to aggregation, dissociation and glycation, could have been hypothesized

The structure of milk proteins versus their functional properties

W pracy przedstawiono i zanalizowano wyniki badań dotyczących zależności między strukturą białek mleka a ich wybranymi właściwościami funkcjonalnymi. Ważnymi czynnikami wpływającymi na właściwości funkcjonalne białek są wymiary molekularne, hydrofobowość, ładunek i elastyczność. Na właściwości funkcjonalne mają wpływ także takie czynniki zewnętrzne, jak: temperatura, pH, siła jonowa czy obecność innych cząsteczek. Podstawową przyczynę różnic we właściwościach funkcjonalnych między białkami upatruje się w ich odmiennej strukturze. Właściwości funkcjonalne można modyfikować metodami fizycznymi, chemicznymi, enzymatycznymi i genetycznymi. Rozpuszczalność jest właściwością fizykochemiczną, od której mogą zależeć inne właściwości funkcjonalne. Białka mogą adsorbować na granicy faz olej/woda i powietrze/woda i obniżać napięcie powierzchniowe, zmieniając jednocześnie swoją strukturę. Dobre właściwości powierzchniowe białek łączy się ze specyficzną dystrybucją ich reszt hydrofobowych i hydrofilowych w ściśle odizolowane obszary, połączoną z zapewnieniem minimalnej masy cząsteczkowej. Stwierdzono istnienie związku między udziałem struktury α-helikalnej, indukowanej adsorpcją na hydrofobowej powierzchni, a kształtowaniem się zdolności do tworzenia emulsji przez peptydy. W opisywaniu zależności między strukturą a funkcją białek coraz większą rolę zaczynają odgrywać wielowymiarowe metody statystyczne. Znajomość molekularnych podstaw kształtowania się rozpuszczalności, zdolności do tworzenia/stabilizowania emulsji/piany przez białka jest podstawową wiedzą w badaniach nad zastosowaniami białek mleka w żywności o pożądanych i zaprojektowanych cechach.In the paper, results of the study on the relationship between a structure of milk proteins and some selected functional properties of them were presented and analyzed. Several factors, such as: molecular size, hydrophobicity, charge, and flexibility are important for the functional properties of proteins. Additionally, external factors, such as: temperature, pH, ionic strength, and the presence of other molecules influence these functional properties. A distinct structure of individual proteins is considered the main reason why there are differences in functional properties of the proteins. Functional properties can be modified in several ways, e.g. by the physical, chemical, enzymatic, or genetic modification. Other functional properties may also depend on solubility which is a physical-chemical feature. Proteins can adsorb at oil/water and air/water interfaces, and, thereby, they can lower the surface tension; at the same time, they also change their structure. Good interfacial properties of proteins are attributed both to the specific distribution of clustering hydrophilic and hydrophobic residues into exactingly isolated zones and to the minimum molecular mass of the peptide enabling this distribution. It was stated that there was a relationship between the α-helical adsorption-induced structure on the hydrophobic surface and the emulsion forming ability of peptides. Advanced statistical methods become more and more popular and they are used to describe the structure-function relationships of proteins. The knowledge of molecular basis of proteins solubility, and foam/emulsion forming/stabilizing abilities is fundamental for the purpose of studying the milk proteins applications in food with required and design properties

Diet-related nature of food enteropathy as exemplified by celiac disease

W pracy przedstawiono i zanalizowano wyniki badań dotyczących etiologii, objawów klinicznych, aspektów molekularnych i analitycznych oraz znaczenia żywienia w celiakii. Celiakia jest enteropatią glutenową, w której występują zmiany w błonie śluzowej jelita czczego odpowiadające morfologicznie na leczenie dietą bezglutenową. Jest ona najszerzej badaną chorobą żołądkowo-jelitową o podłożu autoimmunologicznym wywołaną obecnością w diecie białek pszenicy, jęczmienia czy żyta. Występowanie celiakii wyjaśnia kilka hipotez tłumaczących mechanizm prowadzący do uszkodzenia błony śluzowej jelita cienkiego. U pacjentów chorych na celiakię stwierdzono podwyższony poziom transglutaminazy tkankowej i sugerowano, że fakt ten może odgrywać kluczową rolę w etiologii tej choroby. Stwierdzono, że szkodliwość prolamin zbóż zależy od ich struktury, czyli rodzaju i kolejności aminokwasów zawartych w ich łańcuchach polipeptydowych. Peptydy z A-gliadyny, których toksyczność potwierdzono w badaniach in vivo, zawsze zawierają jeden z czterech motywów sekwencji aminokwasowych tj.: PSQQ; QQQP; QQPY lub QPYP. Stwierdzono fundamentalne znaczenie prawidłowo skomponowanej diety w profilaktyce celiakii. Jak dotąd nie rozstrzygnięto kontrowersji co do toksyczności aweniny owsa dla osób chorych na celiakię.Results of the study on the etiology, clinical symptoms, molecular and analytical aspects, as well as the importance of nourishment for celiac disease were presented and analyzed in the paper. Celiac disease is the gluten enteropathy with the alterations of the mucous membrane of the small intestine that respond to the nongluten-diet treatment. It is one of the most widespread studied autoimmune disease of the small intestine and the stomach that is induced by ingestion of gluten proteins from wheat, barley, or rye. A few hypotheses explain the mechanism leading to the destruction of the small intestine villous structure. The increased content of the tissue transglutaminase was found for celiac patients and was suggested to play the key role in celiac etiology. It has been demonstrated that the toxicity of cereals prolamins depends on their structure i.e. amino acid types and sequences in their polypeptide chains. The peptides from A-gliadin, whose toxicity was confirmed with in vivo assays, always contain one of the four motifs of amino acid sequences: PSQQ; QQQP; QQPY or QPYP. It was found that properly constructed diet has the basic importance in the preventive treatment of celiac disease. So far, the controversy concerning the toxicity of oat avenin for celiac patients is unsolved

Biologicznie aktywne skladniki zywnosci funkcjonalnej w profilaktyce chorob nowotworowych

Zastosowanie biologicznie aktywnych substancji w profilaktyce chorób nowotworowych budzi duże zainteresowanie zarówno przemysłu spożywczego, jak i farmaceutycznego. Powiększający się asortyment produktów zaliczanych do żywności funkcjonalnej stwarza szansę świadomego kształtowania diety w aspekcie szeroko rozumianej profilaktyki nowotworowej. W publikacji omówiono niektóre biologicznie aktywne składniki żywności funkcjonalnej, które mogą odgrywać ważną rolę w zmniejszaniu ryzyka powstawania nowotworów.The application of biologically active components of food for the cancer diseases prevention excite a great interest of food and pharmaceutical industry. The broadening assortment of the functional food products creates a chance for introducing then in diet planning. The biologically active components of functional food can be widely applied as a element of cancer prevention. In the paper bioactive components of functional food, which may play an important role in decreasing of the risk of cancer diseases were described

Some properties of β-casein modified via phosphatase

Modifiedß-casein forms were prepared with acid/alkaline phosphatase. The choice between acid and alkaline phosphatases was critical for the physico-chemical properties ofß-casein. Removal of phosphoryl groups fromß-casein via alkaline phosphatase increased the retention time measured using RP-HPLC and did not change the second-derivative UV spectra. Moreover, the pI value shifted to neutral pH and the solubility decreased, especially at the alkaline pH range.ß-Casein modified enzymatically via alkaline phosphatase formed a foam with volume and stability similar to that formed with intact one. In turn, a dramatic decrease in foam stability was found forß-casein modified via acid phosphatase. Chromatographic, spectral and electrophoretic results suggest proteolytic acivity of acid phosphatase preparation

Fish proteins as an example of immunological food hypersensitivity

Niepożądane reakcje organizmu człowieka związane ze spożyciem żywności to nietolerancje pokarmowe lub alergie. Immunologiczna odpowiedź organizmu na składniki żywności jest wywoływana przez wiele czynników. Alergia objawia się w postaci wielu niespecyficznych reakcji. Epitopy białek, odpowiadające za oddziaływania z przeciwciałami dzielimy na liniowe (ciągłe fragmenty łańcucha białkowego) i konformacyjne (reszty aminokwasowe sąsiadujące w wyniku tworzenia struktury drugo- i trzeciorzędowej). Białka posiadające epitopy o podobnej budowie mogą wykazywać reakcje krzyżowe. Wśród alergii pokarmowych ważne miejsce zajmuje immunologiczna nadwrażliwość pokarmowa na białka ryb. Stabilność termiczna białek ryb powoduje, że zachowują one właściwości alergenne pomimo stosowanych procesów technologicznych. Molekularne aspekty identyfikacji i charakterystyki alergenów pokarmowych, w tym alergenów ryb, są podstawą ich wykorzystania w praktyce klinicznej. W niniejszej pracy scharakteryzowano immunologiczną nadwrażliwość pokarmową na przykładzie białek ryb, molekularne aspekty alergennych białek ryb oraz wybrane metody ich identyfikacji.Food allergy concerns about 1-10% of the population. Adverse reactions of human organism, associated with food consumption, include nonallergic food hypersensi-tivities and food allergy. Many factors cause the human organism immunological response to food ingredients. Epitopes can be divided into linear and conformational. Proteins that are structurally related epitopes may exhibit cross-reactions. Allergy is manifested as many nonspecific reactions, for example: associated with the secretion of IgE and not associated with this process. Abdominal pain, diarrhoea, nausea, rhinitis, dyspnoeic attacks, tightness of the chest, angioedema, rash, urticaria are the examples of the symptoms of food allergy. Many factors associated with the foods processing can change food proteins allergenicity. These processes are related to: preparation of raw materials (e.g. washing, storage, slicing); thermal processing (e.g. drying, heating, cooling, freezing); biochemical treatment (e.g. fermentations); isolation and purification of food ingredients (e.g. centrifugation, extraction, distillation); extended expiration date (e.g. by the addition of alcohol, salt, sugar). The allergy to fish take an important place among food allergies. The prevalence of fish allergy is lower for children (up to 2% of affected children) than adults (5%). The thermal stability of fish proteins causes that they retain the allergenic properties despite the use of technological processes. The use of hydrolysis with proteolytic enzymes may reduce the allergenicity of fish proteins. For fish High Pressure Steaming (HPS) are the most effective method to reduce the possibility of binding of IgE antibodies. Then some patients with immunological fish hypersensitivity can consume canned salmon and tuna. Molecular aspects of the identification and characterization of food allergens, including fish allergens, are the basis for their use in clinical practice. Isolation, purification and identification of fragments responsible for allergies are continuously modified and improved. Bioinformatics and new analytical methods are important tools used for identification of food allergens. Combination of these methods creates additional opportunities for the identification and detection of markers of allergenic proteins responsible for immunological food hypersensitivity. Understanding the mechanisms of allergic reactions and molecular characterization of allergens are important to their diagnosis, therapeutic and prophylactic treatment. In our study we characterized immunological food hypersensitivities exemplified by fish protein, molecular aspects of allergenic fish proteins and selected methods of their identification

Ripened cheese as a source of bioactive peptides

Cheese has a long history in the human diet. In ancient times, cheese was primarily a concentrated form of milk with the benefit of a prolonged shelf life. Recent advances in nutrition science have highlighted the contribution of cheese to nutrition and health. It is a rich source of essential nutrients, in particular, proteins, vitamins, minerals, and also short chain fatty acids. Bioactive peptides from proteins, which are the main subject of this paper, can be generated either by fermentation processes during cheese-manufacturing or by gastrointestinal digestion after consumption. As cheese is a complex food matrix containing a large number of different peptides which change with the ripening time, they are produced during secondary proteolysis through the action of proteinases and peptidases. As long as they are bound in the proteins they are biologically inactive andcan only be active after they have been released from their parent protein. Then, they can exert a wide range of biological activities such as antimicrobial, opioid, blood pressure-lowering, cholesterol-lowering, mineral binding, immunomodulating, and anti-carcinogenic activities. The article discusses the characteristics of cheese, distinguishing it as an important source of bioactive peptides with various activities. Bioavailability of bioactive peptides from cheese was described. The blood-pressure lowering activity was highlighted as milk proteins are the main source of this kind of bioactive peptides, and it is the best-studied and in vivoconfirmed effect. Attention has also been paid to three other activities expressed by bioactive peptides from cheese: anti-carcinogenic, antioxidative, and opioid

Matrix metalloproteinases in urinary system tumors. Part II - Matrix metalloproteinases in urinary bladder carcinoma

Matrix metalloproteinases (MMPs), also referred to as matrixines, provide a group of proteolytic enzymes. They belong to the family of endopeptidases that break down elements of the extracellular matrix, resulting in its continuous remodeling. Their activity is regulated at multiple levels, while tissue inhibitors of metalloproteinases play a major role in this process. Metalloproteinases play a significant part in neoplastic processes due to their contribution to local tumor invasion, the formation of distant metastases, as well as to angiogenesis Urinary tract tumors pose a significant diagnostic and therapeutic challenge and their incidence tends to grow every year. The aim of this second part of the review is to describe the urinary system structure and function, and to highlight the contribution of matrix metalloproteinases to the development of urinary bladder tumor

Action of the chymosin on reconstituted casein systems

The aim of this work was to study the chymosin-catalysed hydrolysis of reconstituted casein systems containing a s1-casein, a  s2-casein, ß-casein and casein or ß-casein modified via chemical glucosylation and/or enzymatic dephosphorylation. The systems containing modified ß-casein instead of casein were destabilised after release of peptides in trace amounts. The coagulation of the systems reconstituted using casein required release of much more peptides than coagulation of those containing modified ß-casein. Proteolysis range in both classes of reconstituted systems was much smaller than proteolysis range in milk. The specificity of chymosin against reconstituted systems was typical. The major proteolysis products were para-casein and caseinomacropeptide in the systems reconstituted using casein as well as fragment 1-23 of a s1 -casein and fragment 193-209 of ß-casein in all the systems used. Only the systems containing casein formed gel with a structure similar to this obtained via casein coagulation in milk