Review: Genetic and protein variants of milk caseins in goats

The milk casein genes in goats, are highly polymorphic genes with numerous synonymous and non-synonymous mutations. So far, 20 protein variants have been reported in goats for alpha-S1-casein, eight for beta-casein, 14 for alpha-S2-casein, and 24 for kappa-casein. This review provides a comprehensive overview on identified milk casein protein variants in goat and non-coding DNA sequence variants with some affecting the expression of the casein genes. The high frequency of some casein protein variants in different goat breeds and geographical regions might reflect specific breeding goals with respect to milk processing characteristics, properties for human nutrition and health, or adaptation to the environment. Because protein names, alongside the discovery of protein variants, go through a historical process, we linked old protein names with new ones that reveal more genetic variability. The haplotypes across the cluster of the four genetically linked casein genes are recommended as a valuable genetic tool for discrimination between breeds, managing genetic diversity within and between goat populations, and breeding strategies. The enormous variation in the casein proteins and genes is crucial for producing milk and dairy products with different properties for human health and nutrition, and for genetic improvement depending on local breeding goals.

Antimicrobial bioactive peptides from goat Milk proteins: In silico prediction and analysis

The main goal of this study was to assess the potential proteins of goat milk (i.e. α-s1-casein, α-s2-casein, β-casein, κ-casein, α-lactoglobulin and β-lactalbumin) as precursors of antimicrobial peptides (AMPs). Bioinformatics tools such as BIOPEP-UWM (enzyme action) were used for the in silico gastrointestinal digestion via a cocktail of pepsin, trypsin, and chymotrypsin A. The antimicrobial activity of peptides was predicted by using four algorithms, including Random Forest, Support Vector Machines, Artificial Neural Network and Discriminant Analysis on CAMPR3 online server, which works on Hidden Markov Models. Different online tools predicted the physiochemical properties, allergenicity, and toxicity of peptides as well. In silico gastrointestinal digestion simulation of proteins by enzymes cocktail yielded a total of 83 potential AMPs, with thirteen peptides being confident by all four algorithms. More AMPs were released from β-casein (21) than from β-lactoglobulin (16), α-s1-casein (15), α-s2-casein (12), κ-casein (11) and α-lactalbumin (9). A total of 17 peptides were cationic, and the majority of the peptides were extended AMPs. These peptides were released from α-s1-casein (SGK, IQK), α-s2-casein (SIR, AIH, TQPK), β-casein (GPVR, AVPQR, AIAR, GVPK, SQPK, PVPQK, IH, VPK), k-casein (AIPPK, QQR, IAK, TVPAK). All of the AMPs were anticipated to be non-toxic, and 54 of the 83 peptides were confirmed to be non-allergic, with the remaining 29 suspected of being allergenic and 31 to be predicted to have good water solubility. Further the molecular docking was used to evaluate the potent dihydropteroate synthase (DHPS) inhibitors. On the basis of ligand binding energy, 17 predicted AMPs were selected and then analyzed by AutoDock tools. Among the 17 AMPs, 3 AMPs were predicted as high-potent antimicrobial. Based on these findings, in silico investigations reveal that proteins of goat milk are a potential source of AMPs. These peptides can be synthesized and improved for use in the food sector. PRACTICAL APPLICATIONS: Goat milk is regarded as a high-quality milk protein source. According to this study, goat milk protein is a possible source of AMPs, and therefore, most important AMPs can be synthesized and developed for use in the food sector.

Novel sensitive monoclonal antibody based competitive enzyme-linked immunosorbent assay for the detection of raw and processed bovine beta-casein

Cow milk protein allergy (CMPA) is the most common childhood food allergy, which can sometimes persist or can newly develop in adulthood with severe symptoms. CMPA's treatment is complete dietary avoidance of milk proteins. To achieve this task, patients have to be aware of milk proteins found as "hidden allergens" in food commodities. In regard to milk proteins, it has been reported that allergenicity of caseins remains unaffected upon heat treatment. For these reasons, we aimed to obtain monoclonal antibodies (mAbs) against native and denatured β-casein, one of the most abundant and antigenic caseins, in order to develop an indirect competitive ELISA (icELISA) to detect and quantify traces of this milk allergen in raw and processed foodstuffs. We developed two specific hybridoma clones, 1H3 and 6A12, which recognized β-casein in its denatured and native conformations by indirect ELISA (iELISA). Cross-reaction analysis by Western blot and iELISA indicated that these mAbs specifically recognized β-casein from bovine and goat milk extracts, while they did not cross-react with proteins present in other food matrixes. These highly specific mAbs enabled the development of sensitive, reliable and reproducible icELISAs to detect and quantify this milk protein allergen in food commodities. The extraction of β-casein from foodstuff was efficiently carried out at 60°C for 15 minutes, using an extraction buffer containing 1% SDS. The present study establishes a valid 1H3 based-icELISA, which allows the detection and quantification -0.29 ppm and 0.80 ppm, respectively- of small amounts of β-casein in raw and processed foods. Furthermore, we were able to detect milk contamination in incurred food samples with the same sensitivity as a commercial sandwich ELISA thus showing that this icELISA constitutes a reliable analytical method for control strategies in food industry and allergy prevention.