Detection of whey fraction common proteins of human and goat colostrum by maldi-TOF/TOF

Human milk is an important source for the breastfed infants as it provides a digestible source of amino acids to infants and also has an immunological protection and assist in developmental functions as well. Therefore, the role of human milk in infant development is well established due to the presence of proteins that are found in differrent fractions of human milk, which are milk fat globule membrane (MFGM) proteins and skimmed colostrum proteins composed of whey proteins and caseins. One of the main difference observed in human milk when compared with other species' milk is that the whey fraction of the skim milk is the major protein source. Therefore, it is important to determine the proteomic profile of the whey fraction in order to better understand milk biogenesis and milk protein functions. The aim of this study is to determine shared whey proteins in the skim fraction of human and goat colostrums via proteomic analysis in the field of contributing towards determining the protein contents of a human milk substitute. In order to assess the proteomic differences and/or similarities between human and goat colostrum, the samples from healthy mothers (n=6) and healthy goats (n=6), collected at early stages of lactation (i.e. 12-24 hours postpartum) were analyzed using DIGE electrophoresis. Master images constructed from both sample groups were compared to differentially expressed proteins, which were then be excised from the gels, trypsin digested and run on MALDI-TOF/TOF mass spectrometer for identification. According to the data obtained from MALDI-TOF/TOF mass spectrometry analysis, 422 overlapped spots were found on the selected master gel of human colostrum and goat colostrum. According to the mass spectrometry data, 270 different proteins were detected in both human and goat colostrum samples. As for the overlapped spots; immunoglobulin, casein, lactoferrin, lactoglobulin, albumin lactotransferrin and lactalbumin originated proteins were mostly identified high abundant proteins. In addition, low abundant proteins such as α1-antitrypsin, integrin, cathelicidin, galectin-3-binding protein, lactadherin, tenascin ve apoliprotein J were also identified. The results obtained from this study represent an important concept as goat's kolostrum might be considered as an alternative substitute of human milk in the future. Although further studies are required to establish the proteomic profile differences seen in human and goat colostrums, this preliminary study underlies the importance of manufacturing high quality dairy products or infants formulas.