Hen egg yolk

The 216-residue hen egg yolk storage protein phosvitin contains 123 serine residues, most of which have been phosphorylated (Eq. 2-16).295 A basic protein of the myelin sheath of neurons contains as many as 6 specific residues of citrulline (Eq. 2-19).296 An adhesive protein from the foot of a marine mollusk contains -80 repeated sequences containing hydroxy-proline 2,3-dihydroxyproline and 3,4-dihydroxyphenylalanine (Dopa) 297/298... 

Anton, M., Martinet, V., Dalgalarrondo, M., Beaumal, V., David-Briand, E., Rabesona, H. 2003. Chemical and structural characterisation of low-density lipoproteins purified from hen egg yolk. Food Chem 83 175-183. 

Le Denmat, M., Anton, M., Beaumal, V., and Gandemer, G. 1999. Characterization of the interface of oil-in-water emulsions prepared with hen egg yolk at different pH and NaCl concentrations. Proceedings VIII European Symposium on the Quality of Eggs and Eggs Products, Bologna, Italy, pp. 325-332. 

The extraction and purification of serum-derived immunoglobulin fraction in hen egg yolk by the combined treatment of the raw egg yolk with caprylic acid and ammonium sulfate has been reported.64 This simple two-step method proved to be rapid, reproducible, and suitable for batch processing of pooled egg yolks. The extraction procedure had no adverse effects on antibody titer. Caprylic acid is, in fact, a natural substance the concentration of autologous caprylic acid in serum is in the range of 40 ppm.65 No adverse effect of caprylic acid should be expected because of traces present in a pharmaceutical solution. Caprylic acid has a low toxicity for vertebrates but acts as a bacteriostatic agent. 

The second (functional) aspect of this problem eoneems the development of pathologic symptoms, the moleeular causes of which are not due to AChE inhibition. One of the first cases of OP nonanticholinesterase effeets (when the association between the OP molecular target and the functional disturbance has been proved) involved inhibition of kinurenin formamidase of the hen egg yolk sac membrane responsible for teratogenic effects (Seifert and Casida, 1978). Another example of OP teratogenic effect is abnormal development of the conjunctival tissue of Xen-opus embryos due to inhibition of lysyloxidase and incomplete post-translational modification of collagen (Snawder and Chambers, 1993). 

Phosvitin is the principal phosphoprotein of egg yolk. Hen egg yolk phosvitin contains 10% phosphate by weight with 120 of the total 222 residues per mole (MW 35,500) phosphorylated. There are 119 residues of phosphoserine and one residue of phosphothreonine. About 5-7 of the total serine residues of phosvitin are not phosphorylated (97). A distinctive feature of the primary sequence of phosvitin is the repeating units of phosphoserine followed by a basic amino acid residue (72). This is illustrated by the following nine sequences of amino acids found in phosvitin ... 

Cossignani, L., et al. 1994. Incorporation of n-3 PUFA into hen egg yolk lipids. II. Structural analysis of triacylglycerols, phosphatidylcholines and phosphatidylethanolamine, Ital. J. Food Set, 3, 293. 

Anton, M., Demnat, M., and Gandemer, G. 2000. Thermostabihty of hen egg yolk granules Contribution of native structure of granules, J. Food ScL, 65, 581. 

Burley, R.W., Evans, A.J. Pearson, J.A. (1993). Molecular aspects of the synthesis and deposition of hens egg yolk with special reference to low density lipoprotein. Poult. Sci., 72, 850-5. 

Although, to date, many different, physiologically relevant lipid mixtures (blood, Hpoproteins, cells, etc.) have been investigated using MALDI-MS, investigations with these mixtures are not always straightforward because (i) there is often only a quite Umited interest in a particular system (ii) the mixtures are normally very complicated and (iii) the experiments are often difficult to repeat because the systems discussed are not readily available. Hence, attention will be focused here on a simple system, namely an organic extract from hen egg yolk [117]. 

Hen egg yolk is a rich source of PLs, where the individual PLs are present in totally different amounts. For instance, PC comprises about two-thirds of the total PL, while PI constitutes less than 1%. Consequently, the hen egg yolk extract serves as an excellent example to investigate dynamic range problems. 

Figure 7.6 Positive-ion MALDI-TOF mass spectra of an organic extract from hen egg yolk, (a) Trace recorded in the presence of DHB (b) Trace recorded in the presence of 9-aminoacridine (9-AA). Peaks are labeled...

A second, alternative, approach employed a readily available N2 laser and standard DHB as matrix [169]. In this case, a dedicated adapter target was used to introduce the TLC plate into the mass spectrometer, and the plate (which had an aluminum back to ensure electric conductivity) was then simply mounted onto the target using conductive adhesive tape (dedicated TLC adapter targets are now also commerciaUy available [170]). A selected TLC lane of a separated hen egg yolk extract, and some selected positive-ion MALDI mass spectra recorded directly from the developed TLC plate, are shown in Figure 7.10. 

Two facts are particularly remarkable here. First, even rather minor fractions of, for example, PI can be easily analyzed and will produce spectra with a reasonable SNR. As PI comprises only about 0.5% of the total PLs of hen egg yolk [169], this clearly proves that a significant dynamic range of more than two orders of magnitude can be achieved. Second, the lower and upper parts of the PE spot provided significantly different mass spectra, whereby PEs with longer fatty acyl (in particular, arachidonoyl) residues were detected in the upper part of the spot, and PEs with shorter acyl residues in the lower part. This was a clear indication that even the separation quahty obtained under normal phase conditions would be sufficient to allow the differentiation of fatty acyl residues if MS were to be used for the subsequent analysis [169]. Somewhat astonishingly, this separation efficiency is simultaneously disadvantageous because, as the total intensity is distributed over several bands, the quantitative data analysis by MALDI-MS becomes... 

FIGURE 13.5 Positive ion MALDI-TOF mass spectra of hen egg yolk PE recorded directly from TLC plates with different thicknesses of the stationary phase. The thickness of the used HPTLC plates is indicated in the figure. Spectra labeled with Control correspond to the PE mixture desorbed directly from a conventional stainless steel MALDI target. Only selected mass spectra are shown. Note that reasonable peak intensities can be exclusively achieved in the case of a reduced silica gel thickness, but not if 200- xm plates are used. (From Griesinger, H. et al., Anal. Biochem., 451,45-47, 2014. With permission.)... 

Mine, Y. (1998) Emulsifying characterization of hens egg yolk proteins in oil-in-water emulsions. Food Hydrocolloid., 12,409. 

Anton, M. and Gandemer, G. (1999) Effect of pH on interface composition and on qnality of oU-in-water emulsions made with hen egg yolk. Colloid. Surface. B-Biointerface., 12,351. 

Teuber, K., Schiller, J., Fuchs, B., Karas, M. and JaskoUa, T.W. (2010) Signihcant sensitivity improvements by matrix optimization A MALDI-TOF mass spectrometric study of lipids from hen egg yolk. Chem. Phys. Lipids 163,552-560. 

Szymczyk, B. and Pisulewski, P.M., Effects of dietary conjugated linoleic acid on fatty acid composition and cholesterol content of hen egg yolks, Br. J. Nutr., 90, 93-99, 2003. 

In an investigation carried out by Chargaff (37), the content of the phosphorus of free lecithin and cephalin, of the combined phosphatides accompanying the vitellin fraction, and of the vitellin fraction were investigated. While about 50% of the phosphatides present in yolk, the free phosphatides, can be extracted with ether, the remainder, the combined phosphatides, are present as a constituent of the lipide-protein complex, lipovitellin, contained in hen egg yolk. 

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