In-depth analysis of the chicken egg white proteome using an LTQ Orbitrap Velos

Karlheinz Mann,Matthias Mann

doi:10.1186/1477-5956-9-7

Abstract

BackgroundHen's egg white has been the subject of intensive chemical, biochemical and food technological research for many decades, because of its importance in human nutrition, its importance as a source of easily accessible model proteins, and its potential use in biotechnological processes. Recently the arsenal of tools used to study the protein components of egg white has been complemented by mass spectrometry-based proteomic technologies. Application of these fast and sensitive methods has already enabled the identification of a large number of new egg white proteins. Recent technological advances may be expected to further expand the egg white protein inventory.ResultsUsing a dual pressure linear ion trap Orbitrap instrument, the LTQ Orbitrap Velos, in conjunction with data analysis in the MaxQuant software package, we identified 158 proteins in chicken egg white with two or more sequence unique peptides. This group of proteins identified with very high confidence included 79 proteins identified in egg white for the first time. In addition, 44 proteins were identified tentatively.ConclusionsOur results, apart from identifying many new egg white components, indicate that current mass spectrometry technology is sufficiently advanced to permit direct identification of minor components of proteomes dominated by a few major proteins without resorting to indirect techniques, such as chromatographic depletion or peptide library binding, which change the composition of the proteome.

Highlights

Hen’s egg white has been the subject of intensive chemical, biochemical and food technological research for many decades, because of its importance in human nutrition, its importance as a source of accessible model proteins, and its potential use in biotechnological processes
Three repetitions of the experiment resulted in seventy-two raw-files that yielded a total of approximately 61,500 peptides identified and accepted with a peptide posterior error probability (PEP) of
If approximately equal conditions are used between the present study and the peptide library-based study [11] by considering proteins identified with single peptides occurring in at least two experimental data sets, or proteins identified by two or more unique peptides in only one experimental data set, 44 more proteins can be added to the list (Additional file 2: Tentatively identified egg white proteins), resulting in a total of 202 possibly identifications

Summary

Introduction

Hen’s egg white has been the subject of intensive chemical, biochemical and food technological research for many decades, because of its importance in human nutrition, its importance as a source of accessible model proteins, and its potential use in biotechnological processes. The arsenal of tools used to study the protein components of egg white has been complemented by mass spectrometry-based proteomic technologies. The avian egg white functions as a shock-absorber, keeps the yolk in place, constitutes an antimicrobial barrier, and provides water, protein and other nutrients to the developing embryo. Besides these biological roles it is an inexpensive source of high quality protein for food industries, contains proteins of pharmaceutical interest, and proteins that have found widespread use in biomedical research and protein chemistry [1-6]. It was shown recently that, in contrast to the previously proposed mode of action, the beneficial effect of the peptide beads does not appear to be mediated by specific interaction but is instead dominated by simple hydrophobic effects [12]

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Conclusion