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Use of advanced mass spectrometry techniques in the undergraduate setting has burgeoned in the past decade. However, relatively few undergraduate experiments examine the proteomics tools of protein digestion, peptide accurate mass determination, and database searching, also known as peptide mass fingerprinting. In this experiment, biochemistry students digest a protein mixture from egg white using the enzyme trypsin; liquid chromatography electrospray ionization time-of-flight mass spectrometry (LC–ESI-TOF-MS) separates the resulting peptides and determines their accurate masses. Instrument software is used to match these peptides to the sequences of known egg white proteins, obtained from an online source. Students then use online protein database search software to match the peptides to the protein and score the results.

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In the LaboratoryRecently fatty acid methyl esters (FAMEs) have been in the news because they are the chemicals in biodiesel. Articles in this Journal have addressed biodiesel as an alternative, renewable, fuel (1-5) and have described the process of creating, identifying, and measuring FAMEs from natural sources, including vegetable oil (3,(6)(7)(8), olive oil (4), peanut oil (2, 6), nutmeg (6), bacteria (9), leaves (10, 11), and eggs (12-14). Previous articles in this Journal examined the fatty acid content of egg yolk ( 14), or of phosphatidylcholine isolated from egg yolk (12, 13), but none of these articles examined gas chromatography coupled with mass spectrometry (GC-MS). In those experiments, FAMEs were separated using gas chromatography and identified using their retention times.The hen egg is a convenient and inexpensive source of lipids for biochemistry laboratory experiments. Egg yolk contains phosphatidylcholine, phosphatidylethanolamine, triglycerides, sphingomyelin, and small quantities (1% or less) of phosphatidylserine, phosphatidylinositol, phosphatidylglycerol, lysophosphatidylcholine, lysophosphatidylserine, lysophosphatidylethanolamine, galactosylceramide, and cholesterol esters (15); all of these contain fatty acids. The relative fatty acid ratio in eggs can be altered by manipulating the hens' diet (16)(17)(18)(19)(20)(21). Two polyunsaturated fatty acids (PUFA) are essential in the human diet, and these essential fatty acids and others synthesized in the body from them are linked to health benefits (22). Foods containing these particular fatty acids, called omega-3 and omega-6 fatty acids, "are believed to be beneficial for heart health, brain, and eye function, infant development, and alleviating hypertension" (23).

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