You have extracted a biological sample with hexanes (non-polar solvent) in order to isolate all of the lipids inside. In this process you have identified the three most abundant lipids, but their structure is unknown. Previous reports have indicated that this sample contains phosphatidylserine, phosphatidylcholine, triacylglycerides, cholesterol, sphingomyelin, and digalactosyldiacylglycerides. You do not have access to advanced instrumentation but do have access to some biochemical tests.

Treatment of the lipids with the enzyme lipase can be used to hydrolyze fatty acid ester linkages

Treatment with glycosyl hydrolase enzymes can be used to hydrolyze glycosidic bonds or other acetal/ketal functionalities
Ion-exchange chromatography can be used to determine the net molecular charge of the lipids after isolation
The ability of the hydrolyzed lipid components (after steps a and b) to reduce aqueous Cu2+ ions can be visibly observed

The result of the tests are summarized below.

Is glycerol/phosphoglycerol Is Cu2+reduced Net molecular

produced after treatments a/b? after a/b? charge?

Lipid 1 Yes No -1

Lipid 2 Yes Yes 0

Lipid 3 No No 0

a) What information does test d provide to you?

b) Based on the results above, which lipid species is the most likely candidate to be lipid 1? Explain your answer.

c) Based on the results above, which lipid species is the most likely candidate to be lipid 2? Explain your answer.

d) The data from the tests isn't sufficient by itself to conclusively determine the identity of lipid 3, but it is sufficient to eliminate all but two possibilities. What are they?

e) Draw the structure of a beta 1-->6 linked disaccharide of a galactose and a fructose monosaccharide with a 12:1 (delta 9) fatty acid acylated onto the remaining anomeric carbon.