A Hunch about the identity of the mouse pheromone

From the last analysis, the 371 mass species has been hypothesized to be a conjugate between aspartic acid and palmitic acid.

A little digging into the 431 mass species using the formula C24H33NO6, I broke it down to two components: C20H28O3 to react with aspartic acid (C4H7NO4).

Aspartic Acid

The C20H28O3 compound can be Etienic acid (4-androsten-3-one-17beta-carboxylic acid; 3-keto-4-etiochlenic acid;Testosterone 17-beta-carboxylic acid;3-Oxo-4-androstene-17-beta-carboxylic acid), which is basically testosterone with its hydroxyl group turned into a carboxylic group. The conjugated product is:

This would be something that should be produced in the body. The C20H28O3 formula could have alternative structures, notably 4-hydroxyl-retinoic acid and an analog, as the following:

4-hydroxyl-retinoic acid

 It's also worth noting that these three compounds have mass of 316, which is often identified in the LC/MS studies.

Fatty acid-amino acid conjugate has been identified, as elicitor in plant defense. The most famouse is Volicitin:

Which is a hydroxyl-linolenoic acid conjugated to glutamine. Similar compounds have been identified in beetles, caterpillar and fly larvae. The enzyme to make the synthesis is apparently unknown.

Prediction: these compounds (431, 316 and 371) appear in the same fractions, which means that they share similar chemical properties. The prediction is that if this is the case, other amino acid conjugates should also be present, especially the gluatamic acid conjugate. This is worth looking at.

Agilent Result from Loren in CA

Analysis performed:

Using MassHunt software.
1. Identify the peaks in MC38-14 and ME38-15, using peak size 5000 as cutoff, save the peaks in H:\Data\Data2010\PheromoneMSID\MMU\MC-14_ME38-15ionlist.csv.

2. Use the mass in this file to exclude the peaks found in ME38-14 and ME38-15, with a peak cutoff of 1000.
 Save the identified peaks in
H:\Data\Data2010\PheromoneMSID\MMU\ME38&39-14excl.csv.

3. Use the list in this second file, to screen for peaks in ME38-12, ME38-13, ME39-12 and ME39-13. Only peaks matches the masses are selected. Also use peak cutoff at 800. Save file in:
H:\Data\Data2010\PheromoneMSID\MMU\ME38&39-12&13excl_800.csv

4. Use the new list to see if any peak is present in ME39-15.
The candidates with a plus sign in the "candidate" worksheet are potential candidates, while the ones with a "x" are present in comparable level in ME39-15 and are excluded.

Several observations:

1. 316 peaks are found in this list, but they are excludes as real candidate.
2. 431 also found. but too many potential formulas.
3. Large MW candidates are likely column materials.
4. Small MW candidates are too common.

Best candidates:

371.2667	54627	C20 H37 N O5
371.2669	17983	C20 H37 N O5
371.2671	72949	C21 H41 N S2
371.2672	78853	C20 H37 N O5
371.2672	67729	C21 H41 N S2
371.2673	23201	C15 H34 N9 P

After discussion with Shane (10/25/10), we decided that 371.2667/2669, Likely formula: C20H37NO5:
Two candidates are glutamic acid linked to a long chain or an aspartic acid with a long chain.

431.2302	14209	C18 H34 N5 O5 P
431.2306	39474	C24 H33 N O6

Other candidates: C20H29N7O4 (431.2307) =ArgTrpAla