26 Questions 82 Answers 0 Followers
Questions related from Kay Wong
Dear all, I am culturing some suspension cell lines. I am planning to perform proteomics (LC-MS/MS) experiments on them. Unlike adherent cells (viable cells are adhering to the substrate and...
04 March 2020 2,560 3 View
Dear colleagues, I would like to seek your kind advice on click chemistry enrichment of azidohomoalanine (AGA)-tagged proteins. From literature, I learned that there are 2 main avenues, either...
19 February 2020 8,927 2 View
Dear colleagues, We would like to discriminate between populations of a plant species at different geographical locations. Yet, microsatellite markers (to distinguish them) are scarce....
13 October 2017 1,373 5 View
Dear colleagues, Following SCX, we've performed manual desalting of the individually-separated iTRAQ peptide fractions before LC-MS/MS. We used the commercially-available C18 Pipette Tips for the...
24 November 2016 5,132 5 View
Dear colleagues, Our lab is testing a new freeze-dryer's performance, but we are not sure if we've been using it correctly. It's a benchtop type, with a transparent drum manifold, operable at...
01 August 2016 7,606 12 View
Dear colleagues, Hi. Working in a Mass Spectrometry proteomics lab, we are exposed to organic solvents, e.g. Acetonitrile (ACN) from time to time. Upon discarding them (e.g. a few liters) into a...
18 July 2016 210 2 View
Dear colleagues, For proteomics experiments, we've purchased LC-MS grade solvents. These high purity solvents initially have already been 0.1-micron filtered (by the vendor). To play safe,...
29 February 2016 1,652 10 View
Dear colleagues, Hi. I am new to LC-MS/MS proteomics and would like to seek you advice on a few LC configuration: Is peptide pre-concentration using the trap column a must (in the LC-MS/MS first...
02 November 2015 7,822 9 View
Dear colleagues, We are trying to accurately determine the mass of a protein (e.g. 50KDa) by MALDI-TOF. The protein has a concentration of approx. 3 pmol/ul, kept in 30 mM PBS buffer (no other...
20 October 2015 2,267 9 View
Dear colleagues, With access to only one Orbitrap instrument, we are conceiving 2 different LC systems for switching between proteomics (nano-UHPLC) and metabolomics (UHPLC) analyses once a...
27 June 2015 5,068 5 View
Dear colleagues, The new APGC (Atmospheric pressure gas chromatrography) ion source is a new alternative to the conventional EI (in that it provides soft, APCI-like ionization) for GC-MS. I would...
25 May 2015 7,353 3 View
MS or MS/MS?; single quad or triple quad? As a newbie, I find it puzzling with the many different configurations a GC-mass spectrometer can possess (for metabolites identification and...
21 May 2015 4,457 10 View
Dear colleagues, Would you mind sharing your experience regarding nano-LC systems for shotgun quantitative proteomics (MS/MS)? I would also like to explore if any particular nano-LC model that is...
11 May 2015 9,045 2 View
Dear colleagues, Lately I've encountered some confusion regarding the "hybrid-type" Orbitrap mass spectrometer. May you please advice regarding whether the below terminologies are referring to the...
14 April 2015 4,218 5 View
Dear Colleagues, I would like to seek your advice on another question: Lately, Our lab bought a commercial enzyme, and somehow we've run it on a SDS-PAGE gel. Intriguingly, we observed...
10 February 2015 2,796 7 View
Dear colleagues, I am currently performing mass-spec identification on some proteins (from a human cell line origin). Yet, from Mascot database search, some (but not all) instead showed matches to...
06 February 2015 4,351 6 View
Dear colleagues, I tried to analyze some phosphorylated peptides (around 8000 Da) in MALDI-TOF (positive linear mode). However, it's difficult to obtain a high resoultion, very sharp peak....
02 December 2014 6,600 5 View
PEG, being a polymer, tends to interfere with matrix crystallization. As a result of this, it is difficult to produce decent signals in MALDI-TOF (linear positive mode). Would you have any advice...
18 November 2014 522 14 View
Taking peptides (in CHCA matrix) as an example, why would most ions produced carries an 'overall net' +1 charge? As a peptide must contain different combinations of acidic and basic amino acids...
13 November 2014 3,515 8 View
According to the definition by Unimod "Monoisotopic mass is calculated using the mass of the most abundant natural isotope of each constituent element" and "Some sources suggest that monoisotopic...
28 October 2014 9,402 5 View
Hi, I have a real-time PCR assay plate that is ready to run (SYBR green dye, primers, enzyme, template...everything ready). But just prior the run, our instrument suddenly broke down (with an...
05 September 2014 228 5 View
To my knowledge, most such studies used correlation. But as mRNA gives rise to protein (which is a seemingly 'causative' relationship), Isn't that a regression analysis would otherwise be more...
02 September 2014 1,410 10 View
For example, if a tryptic peptide (spanning its N-terminal) could be detected in PMF, and in MS/MS it also matched with a reasonably high Mascot ion score. With such information, do I have...
27 August 2014 8,864 9 View
Hi, I'd like to profile and compare a number of metabolities between cell types. As I am new to LC-MS/MS, please kindly advice which below instrument would be more useful: LTQ Orbitrap...
24 July 2014 8,890 15 View
Hi My ‘MS-compatible Silver-stained’ protein bands produced high quality MALDI-TOF/TOF spectra (many decent peaks with strong signals at both the MS and MSMS level), but are unable to match any...
17 July 2014 8,611 14 View
After downloading the EST genomic database from NCBI GenBank (downloaded from ftp blast databases from NCBI as EST-others, at ftp://ftp.ncbi.nih.gov/blast/db/FASTA/)1. How could I convert the...
08 July 2014 1,157 2 View
