Analysis of low-abundant gut hormone peptides using mass spectrometry

My name is Richard Kay. I'm a senior research associate at the Wellcome Trust-MRC Institute of Metabolic Science at Cambridge University. I use mass spectrometry to measure peptides in plasma and in tissues, specifically, looking at glucohormone peptides such as insulin, glucagon and other peptides related to diabetes.
A good thing about being part of the university linked to hospital is we're very close proximity to the clinical researchers, so you can get hold of samples, and use mass spectrometry to try and help identify the questions that they might have. One of the main challenges of performing peptide mass spectrometry, especially in plasma, is that glucohormone peptides circulate at very low levels, in the region of 1 to 50 picogram per mil.
Insulin circulates up to around about 5 nanogram per mil. So, the concentration of these peptides are very difficult to measure using mass spectrometry without performing extensive sample cleanup preparation. Despite the problems of being able to take low band of peptides like insulin in plasma, mass spectrometry has a good benefit. For example, where we've been looking at insulin autoimmune syndrome, they have proinsulin peptides circulating which cross-react with immunoassays that see peptide in insulin prepared immunoassays, whereas mass spectrometry can tell the difference between the various circulating forms very, very easily, and give you the correct answer.
In our lab, we have two mass spectrometers, a high-resolution mass spectrometer for performing peptidomics experiments, for characterizing and doing untargeted work. We also have a Waters TQ-XS system with an I-Class high-flow rate LC system and an M-Class nano LC system. So, we can use either system for peptide quantitation based on the sensitivity that's required for the peptide of interest.
Our recent work in the insulin autoimmune syndrome, we've collaborated Waters using a Waters SEC column to separate antibody-bound insulin away from the free insulin. And then, we ran the extracts on our TQ-XS. We use the M-class with the TQ-XS because of the superior sensitivity that it enabled us to have when we were looking at insulin, C-peptide and other proinsulin peptides from one single microliter of starting material.
Using size-exclusion chromatographic columns, we loaded a small amount of plasma onto the column, and then separated out the antibody-bound insulin from the free insulin, and collected the eluant into Waters QuanRecovery Plates before injecting those onto the TQ-XS to measure insulin, proinsulin and some intermediate.
The main reason why we use the QuanRecovery plates is the insulin is very sticky, and we lose the peptide if we didn't have a special recovery plate. Where I would like to take my spectrometry going forward is to use the multiplexing capabilities of a mass spectrometer to measure multiple glucohormones within a single analysis to replace the multiple immunoassays that have to be used for each peptide of interest.