Marta Pokora

Egg-yolk protein by-product as a source of ACE-inhibitory peptides obtained with using unconventional proteinase from Asian pumpkin (Cucurbita ficifolia)

UNLABELLED In the present study angiotensin I-converting enzyme (ACE) inhibitory peptides were isolated from egg-yolk protein preparation (YP). Enzymatic hydrolysis conducted using unconventional enzyme from Cucurbita ficifolia (dose: 1000 U/mg of hydrolyzed YP (E/S (w/w)=1:7.52)) was employed to obtain protein hydrolysates. The 4-h hydrolysate exhibited a significant (IC₅₀=482.5 μg/mL) ACE inhibitory activity. Moreover, hydrolysate showed no cytotoxic activity on human and animal cell lines which makes it a very useful multifunctional method for peptide preparation. The compiled isolation procedure (ultrafiltration, size-exclusion chromatography and RP-HPLC) of bioactive peptides from YP hydrolysate resulted in obtaining peptides with the strong ACE inhibitory activity. One homogeneous and three heterogeneous peptide fractions were identified. The peptides were composed of 9-18 amino-acid residues, including mainly arginine and leucine at the N-terminal positions. To confirm the selected bioactive peptide sequences their analogs were chemically synthesized and tested. Peptide LAPSLPGKPKPD showed the strongest ACE inhibitory activity, with IC₅₀ value of 1.97 μmol/L. BIOLOGICAL SIGNIFICANCE Peptides with specific biological activity can be used in pharmaceutical, cosmetic or food industries. Because of their potential role as physiological modulators, as well as theirhigh safety profile, they can be used as natural pharmacological compounds or functional food ingredients. The development of biotechnological solutions to obtain peptides with desired biological activity is already in progress. Studies in this area are focused on using unconventional highly specific enzymes and more efficient methods developed to conduct food process technologies. Natural peptides have many advantages. They are mainly toxicologically safe, have wide spectra of therapeutic actions, exhibit less side effects compared to synthetic drugs and are more efficiently absorbed in the intestinal tract. The complexity of operation of large scale technologies and high cost of purification techniques are limiting factors to the commercialization of food-derived bioactive peptides. Research on the isolation of bioactive peptides in order to reduce the processing time and costs is continuously developing. Bioactive peptides can also be released from protein by-products of the food industry, which reduce the substrate expense and production cost as well as provide the added advantage of an efficient waste disposal. Moreover, proteins as precursors of food-derived peptides are well-tolerated by the human body and therefore their application in drug development may reduce costs and duration of toxicological studies during research, development and clinical trials.

An attractive way of egg white protein by-product use for producing of novel anti-hypertensive peptides

The aim of this study was to (i) examine how enzymatic hydrolysis with a non-commercially available proteinase of fig-leaf gourd fruit (Cucurbita ficifolia) increased the use value of egg white protein preparations, generated as byproducts in the industrial process of lysozyme and cystatin isolation from egg white, and (ii) evaluate the inhibition of angiotensin I-converting enzyme (ACE) by the obtained hydrolysates. Purification procedures including membrane filtration, gel filtration chromatography and reversed-phase high-performance liquid chromatography (RP-HPLC) led to the production of several peptide fractions. Two novel ovalbumin-derived tetrapeptides: SWVE (f 148-151) and DILN (f 86-89) with ACE inhibitory activity were obtained. Study of their inhibitory kinetics revealed a non-competitive binding mode, with an IC50 value against ACE of 33.88 and 73.44 μg for SWVE and DILN, respectively. Synthetic peptides which were designed on the basis of peptide SWVE were examined. A tripeptide sequence of SWV revealed the strongest ACE-inhibitory activity.

Antioxidant and antidiabetic activities of peptides isolated from a hydrolysate of an egg-yolk protein by-product prepared with a proteinase from Asian pumpkin (Cucurbita ficifolia)

Bioactive peptides derived from food have been increasingly popular due to their therapeutic properties. Of particular importance are peptides with a multidirectional activity that can be used in the treatment and prevention of diet-related diseases. This paper attempts to utilize a by-product of phospholipid extraction from egg yolk as a source of peptides with a broad spectrum of biological activity. In addition, in this research we used a non-commercial enzyme obtained from Asian pumpkin, which has not been sufficiently researched in terms of its ability to release biopeptides from food proteins. In the present study the biological properties of peptides, derived from egg-yolk protein by-products (YP) remaining after phospholipid extraction, and their four synthetic analogs were investigated with regard to their antioxidant (radical scavenging capacity, Fe2+ chelating effect, reducing power (FRAP)) and antidiabetic (α-glucosidase and DPP-IV inhibitory activities) properties. One of them, with the sequence LAPSLPGKPKPD, exhibited the highest antioxidant activity (free radical scavenging activity (6.03 μM Troloxeq per mg protein); FRAP (296.07 μg Fe2+ per mg protein)). This peptide also revealed the strongest DPP-IV (361.5 μmol L−1) and α-glucosidase (1065.6 μmol L−1) inhibitory activities, a novel multifunctional effect for peptides from an egg-yolk hydrolysate.

Biological and functional properties of proteolytic enzyme-modified egg protein by-products

Enzymatic hydrolysis led to improve functional properties and biological activity of protein by-products, which can be further used as protein ingredients for food and feed applications. The effects of proteolytic enzyme modification of egg-yolk protein preparation (YP) and white protein preparation (WP), obtained as the by-products left during the course of lecithin, lysozyme, and cystatin isolation on their biological and functional properties, were evaluated by treating a commercial Neutrase. The antihypertensive and antioxidative properties of YP and WP hydrolysates were evaluated based on their angiotensin-converting enzyme (ACE)-inhibitory activity and radical scavenging (DPPH) capacity, ferric reducing power, and chelating of iron activity. The functionality of obtained hydrolysates was also determined. Neutrase caused a degree of hydrolysis (DH) of YP and WP by-products: 27.6% and 20.9%, respectively. In each of them, mixture of peptides with different molecular masses were also observed. YP hydrolysate showed high levels of antioxidant activity. The scavenging capacity, ferric reducing power, and chelating capacity were observed at the level: 0.44 μmol/L Trolox mg−1, 177.35 μg Fe2+ mg−1, and 549.87 μg Fe2+ mg−1, respectively. YP hydrolysate also exhibited significant ACE-inhibitory activity, in which the level was 59.2 μg. Protein solubility was significantly improved as the DH increased. WP hydrolysate showed high water-holding capacity of 43.2. This study indicated that YP and WP hydrolysates could be used in foods as natural antioxidants and functionality enhancers.

Improving the properties of fodder potato protein concentrate by enzymatic hydrolysis.

Protein hydrolysates of profitable properties were prepared from the fodder potato protein concentrate. The hydrolysis process was performed with the use of commercial available enzyme (Alcalase) over a 2 and 4 h incubation period. Chemical and amino acid composition as well as functional properties of resultant hydrolysates were determined. A 2 h long process occurred profitable to obtain preparations of well balanced amino acid composition as well as proved functional properties. The industrial preparation, modified within proteolytic enzyme, totally soluble (average 98%), was characterised by fivefold higher oil holding capacity (average 5.4 cm(3)/g) and much better foam capacity (more than 150%) as compared to the material underwent modification (13.00%, 2.1 cm(3)/g and 5.33%, respectively). Presented results suggested potential use of fodder potato protein not destined directly for food purposes as the suitable product for preparations characterised by high nutritive value and functional properties.

The use of serine protease from Yarrowia lipolytica yeast in the production of biopeptides from denatured egg white proteins

Deriving non-conventional enzymes from cheaper sources than those used for commercially available enzymes may result in the production of hydrolysates with beneficial features, while drastically reducing the cost of hydrolysis. This is especially significant for enzymatic hydrolysis as a method of protein waste utilization. We have previously described the ability of non-commercial serine protease from Yarrowia lipolytica yeast to produce/release bioactive peptides from egg white protein by-products (EP). The enzymatic hydrolysis of EP was carried out for 24 h using the serine protease at an enzyme: substrate ratio of 1:30 (w/w). The obtained hydrolysate was characterized by protein degradation of 38% and also exhibited an antioxidant and cytokine-inducing activity. The isolation procedure (ultrafiltration and RP-HPLC) of bioactive peptides from the EP hydrolysate provided peptide fractions with significant antioxidant and ACE inhibitory activities. Three homogeneous and three heterogeneous peptide fractions were identified using MALDI-TOF/MS and the Mascot Search Results database. The peptides, mainly derived from ovalbumin, were composed of 2-19 amino-acid residues. We have thus demonstrated a novel ability of serine protease from Y. lipolytica to release biopeptides from an EP by-product.