Hi, I have a quick question about quantificaiton of SILAC samples using 13- C6-Lysine as my heavy isotope. I also tried reading through previous threads, and couldn't find a direct answer to this question.
My questions: (1) Does XPRESS support either fixed or variable modifications? (2) I can see that ASAPRatio does, but I can't get that tool to work properly. What am I doing wrong? FOR XPRESS ANALYSIS Fixed Modifications: Carbamidomethylation(C), Monoisotopic mass = 160.0306487 Variable Modifications: Oxidized Methionine(M), Monoisotopic mass = 147.035 Pyroglutamic Acid(E), Monoisotopic mass = 112.0160439 I'm using 13-C6-Lysine as my heavy isotope, Monoisotopic mass = 134.115092 The settings I'm using in XPRESS: Change XPRESS mass tolerance: 0.1 Change XPRESS residue mass difference: K, 6.02012902 How do I input the fixed and/or variable modifications listed above? FOR ASAP RATIO ANALYSIS Change labeled residues to: K m/z range to include in summation of peak: 0.05 Specified residue mass 1: M, 147.035 Specified residue mass 2: C, 160.0306487 Specified residue mass 3: E, 112.0160439 Results: (1) XPRESS quantifies a ratio of heavy/light and gives me a ratio, however this analysis does not take into account any fixed or variable modifications discussed above. (2) ASAPRatio result is always "-1 +/- -1" and no chromatogram is displayed when I click on that link. Any ideas what I may be doing wrong? Thank you VERY MUCH for your help, Cyrus -- You received this message because you are subscribed to the Google Groups "spctools-discuss" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/spctools-discuss?hl=en.
