Richard Kay

Didn't see much active GLP-I in our LC-MS analyses. Vast majority is 1-36 or 1-37.

www.medschl.cam.ac.uk/characterisi...

We have a potential MRC iCASE PhD with AstraZeneca using mass spectrometric techniques to identify the destination organs of endogenous and exogenous peptide hormones. This should be a really interesting PhD, using both ours and AstraZeneca's expertise and mass spectrometry instrumentation.

Where do injected peptide weight loss drugs end up in the body? What about known and currently uncharacterised peptides produced in the gut - where do they go? Want to help myself and Andreas Dannhorn from AstraZeneca try and find out how to do this?

*Orbitrap... Stupid autocorrect...

Orbital Astrals and ZenoToFs are cool and all... But do you have Mass Specs??

Have a good weekend everyone!

#teammassspec

Have done that and we get a match for the de-glycosylated peptide (strong signal too) I just can't find the glycosylated one. Have even drawn up some theoretical structures of the peptide to try identify peaks..

Yes. Pretty short. I can just about make out y1, 2 and 3..

I have a clearly glycosylated peptide, which I think is an elusive peptide I am after, but it gives almost no peptide fragments. I asked ChatGPT for some help interpreting glycopeptide MS/MS spectra, it generated this abomination.. I think our jobs are secure for a little longer yet...

The last ticket machine at Ely station printing the orange tickets has betrayed me.

Printing out the stupid slippery QR tickets that are 2.5 times the size of the old ones... Grrr..

Interestingly - metformin is being investigated as a prophylactic for nausea and vomiting in pregnancy. It does this by raising GDF15 prior to its meteoric plasma spike during the gestational period.

Mounjaro is a clever peptide, a mixture of three.. GIP, GLP-1 and a peptide from lizard venom!

This becomes worse when they come off and put weight on again - having lost muscle mass in the weight loss process.

The BMJ released an article about this recently.

Weight loss treatment should come with exercise as well to stave off muscle loss..

They are amazing - they way they have extended half lives of endogenous peptides from 3 mins to 3.5 days is phenomenal.

The issue could be that they are worried about side effects. One issue is lean muscle mass loss (as well as fat). If this is lost, then it can also be harmful.

I am a regular volunteer for our studies, but we are unlikely to get ethics to dose healthy subject with them.

The switching off of "food noise" in some people is very effective, but in those who don't have this it could be dangerous.

Apparently, when you stop taking them, the voices return.

Our group are doing research with both these peptides and how they change other gut hormones. We are performing clinical studies in specific disease states, however getting similar data from healthy individuals in our clinic is an issue, as with these peptides blunt appetite so much!

The lab next door to me use an MSD multiplex kit that can get to sub pg/mL.

Not a mass spec based approach, but it also measures lots of other interleukins as well.

The 1031.58 ion is a dimer of 516, which shows up if it is selected for MS/MS.

That potentially could be an in-source dimer. They only have 1+, but are double the m/z (well, double the m/z -1)

Probably highly unlikely, but we get contaminants in our extracts (problematic bile salts..) that sometimes form in-source dimers. We see a singly charged ion of ~1031m/z, which is actually a dimer of a compound of 516 m/z. Probably highly unlikely...

In these specific disease states, the plasma level finally crept above the LC-MS/MS (and immunoassay) detection limit for a little while - as with most peptides it has a maddenignly short half life.

A very hard peptide to find and analyse... a big tick against that one!!

Insulin Like Peptides 5 (INSL5) circulates at very low levels, it is hydrophobic, causes horrible carryover, has poor fragmentation in MS/MS, and to top it off it is only produced in the distal colon from cells that total 0.1-1% of all gut epithelial cells.

One of those peptides....

Discovery of role of gut hormone in chronic diarrhoea could aid development of new tests and treatments High levels of a hormone found in cells in the gut could underlie many cases of chronic diarrhoea and help explain up to 40% of cases of patients with

An article on the Cambridge University website about a challenging peptide I have worked on for over a decade.

@cabannon.bsky.social and the rest of the project team showed it was raised in plasma from patients with bile acid diarrhea and inflammatory gut diseases.

www.cam.ac.uk/research/new...

Discovery of role of gut hormone in chronic diarrhoea could aid development of new tests and treatments High levels of a hormone found in cells in the gut could underlie many cases of chronic diarrhoea and help explain up to 40% of cases of patients with

Interview on our published paper last week describing how an identified gut hormone is involved in symptoms of patients with chronic diarrhoea:

www.cam.ac.uk/research/new...

And here is the paper on INSL5. LC-MS/MS analysis generated similar concentration data compared to an ELISA. The peptide circulates at 100's of pg/mL in disease state, and almost undetectable in control individuals.

Gut has an impact factor of 25 - nice!

We confirmed the antibody worked by IP-MS - which gave almost the same LC-MS signal as our standard peptidomics extraction. The IP-MS was much cleaner extract though! The paper shows this - Will post it when we get the final version!

Thanks! A really challenging peptide to analyse.

We had help from your company who developed an antibody to the peptide - the first that actually measured the right compound.

Other antibodies are junk...we confirmed your antibody measured the right thing using LC-MS/MS

Well - we finally found insulin like peptide 5 in blood using LC-MS/MS. Have been working on this since 2013 - when at my old lab!

It is raised in patients with bile acid diarrhea - and when you dose bile rectally...

Paper just accepted in Gut - will be out soon!

Stil very low ~ 100 pg/mL