Finally! A ready-to-run human plasma proteomics standard!

 

Disclaimer: I'm going to ramble about a new commercial product that was totally my idea and if you buy it I'll probably get money back for a whole lot of enzymes I personally bought. This was actually a tough post to write that I deleted and re-typed several times because it seems antithetical (which might be a thing) to this whole blog thing. Meh.

Ramble: 

I had a few months between my academic appointments which ended up being a top notch sabbatical, and that's what I'm going to call it from now on. I consulted for some really cool companies, found time to gracefully exit the CRO thing I founded several years ago, and got a really up-to-date view of what dozens of companies in proteomics are doing these days. During the consulting bit I'd sometimes go places or remote log in to instruments and help with experiment optimization. 

Everyone had the K562 proteomic digest from Promega or the HeLa digest from Thermo/Pierce. Add formic acid, inject it, it should look the same on identical instrument configurations regardless of where you are. 

Unfortunately, almost everyone actually wanted to do blood/plasma proteomics. And these things couldn't be more different. More than 90% of blood is composed of 1 protein and 95% of it is composed of like 14 proteins. That's not what the proteome is of cancer cells with 150 chromosomes which are full almost to bursting trying to express every protein in their entire genome. A great K562 method might give you plasma proteins, but it's not going to be great. It's tough to find 2 things in proteomics that are more different. 

So I went and batch prepped some plasma so I had a standard that I could use to compare things for the companies I was working with - and it was awesome. I also had comparator data because it was a sample I'd used before on multiple instruments over the years, and I ain't changed my bulk proteomics sample prep method since 2017. 

Then I was like - wait. WTF. Shouldn't there be a commercially available one? Why isn't there a commercially available plasma proteome tryptic digest?? 

How hard and expensive could that be? 

Oh. Oh ye of excessive confidence. 

But now you can just buy the first successful attempt at a standard - Equalizer I - from ESI source solutions! It's just a neat plasma digest, so it's ridiculously insanely hard to see anything besides albumin and immunoglobulins and about 100 other things, which is the exact opposite of the cancer cell line digest. Again, very clearly biased, but if no one ever buys it, I honestly don't care because I won't ever have to prep a plasma proteome digest ever again in my life and I've personally got something to do method development on. If anyone else finds it useful, we tried hard to keep the price down and $375 will get you 100x 200ng injections along with comparator data from 6 different instruments or something (a number I hope will grow soon).