The chicken egg yolk plasma and granule proteomes

Abstract

Using 1-D SDS-PAGE, LC-MS/MS, and MS(3), we identified 119 proteins from chicken egg yolk, 86 of which were not identified in yolk previously. Proteins were roughly quantitated by calculating their exponentially modified protein abundance index (emPAI) to classify them as major or minor yolk components, and to estimate their distribution between yolk plasma and yolk granular fraction. The proteins with highest abundance were serum albumin, the vitellogenin cleavage products, apovitellenins, IgY, ovalbumin, and 12 kDa serum protein with cross-reactivity to beta2-microglobulin. In addition yolk contained many other serum and egg white proteins, the proteases nothepsin and thrombin, numerous protease inhibitors, and antioxidative enzymes, such as superoxide dismutase and glutathione peroxidase. Among the moderately abundant proteins were two alpha2-macroglobulin-like proteins different from egg white alpha2-macroglobulin, and the major biotin-binding protein of yolk. An unexpected identification was that of the eggshell matrix protein ovocleidin-116, which was previously thought to be eggshell-specific. The list of chicken egg yolk proteins provided in this report is by far the most comprehensive at present and may serve as a starting point for the characterization of less well-known yolk proteins.

The Unique Features of Proteins Depicting the Chicken Amniotic Fluid

“…Overall, it is noteworthy that on the ten most abundant proteins in the chicken AF, four of them are major egg white proteins (OVAL, SPINK7, LYZ, TF) (42) whereas ALB, APOA1, GC, TTR, APOC3 are egg yolk abundant proteins (43). The gene expression of OVAL, SPINK7, LYZ and TF, which together account for about 80% of the egg white proteins, is under hormonal control in the oviduct and will not be expressed until the onset of sexual maturity of hens (44).…”

“…As for LYZ, the ongoing hypothesis is that it also originates from egg white although it is also expressed by a wide range of tissues (45). On the other hand, APOA1, ALB, GC, TTR and APOC3 represent highly-abundant proteins of egg yolk (43), which also suggests that they are somehow transferred to the chicken AF from the egg yolk, or from the yolk sac where they are highly expressed (4). The molecular mechanisms by which egg white and egg yolk proteins enter the AF during the first half of incubation are still not completely solved (16,18).…”

Changes in activity during storage and characteristics of superoxide dismutase from hen eggs (Gallus gallus domesticus)

“…Out of this number, 86 fractions were described for the first time. Majority of detected fractions were present in both yolk and white but in different concentrations [2].…”

“…In chicken erythrocytes, the presence of isozymes of Cu/Zn SOD with molecular mass of 30-31 and 15 kDa was confirmed [15,16]. Mann and Mann described a protein similar to extracellular SOD with molecular mass of 31-37 kDa in chicken yolk plasma [2].…”

“…They provide with high-quality nutritive proteins. It is known that majority of these proteins come from blood, but some may be produced locally [2].…”