Complexity, cost, and content – three important factors for translation of clinical protein mass spectrometry tests, and the case for apolipoprotein C-III proteoform testing

Abstract

<jats:title>Abstract</jats:title><jats:p>Complexity, cost, and content are three important factors that can impede translation of clinical protein mass spectrometry (MS) tests at a larger scale. Complexity stems from the many components/steps involved in bottom-up protein MS workflows, making them significantly more complicated than enzymatic immunoassays (EIA) that currently dominate clinical testing. This complexity inevitably leads to increased costs, which is detrimental in the price-competitive clinical marketplace. To successfully compete, new clinical protein MS tests need to offer something new and unique that EIAs cannot – a new content of proteoform detection. The preferred method for proteoform profiling is intact protein MS analysis, in which all proteins are measured as intact species thus allowing discovery of new proteoforms. To illustrate the importance of intact proteoform testing with MS and its potential clinical implications, we discuss here recent findings from multiple studies on the distribution of apolipoprotein C-III proteoforms and their correlations with key clinical measures of dyslipidemia. Such studies are only made possible with assays that are low in cost, avoid unnecessary complexity, and are unique in providing the content of proteoforms.</jats:p>

Apolipoprotein C‐III O‐glycoform profiling of 500 serum samples by matrix‐assisted laser desorption/ionization mass spectrometry for diagnosis of congenital disorders of glycosylation

“…Furthermore, apoCIII with GalGalNAc (T-antigen, Core1) and NeuAcGalGalNAc (Sia3Core1) or Gal (NeuAc)GalNAc (SIa6Core1), and unglycosylated apoCIII is also present. [12][13][14] ApoCIII was first analyzed for the purpose of identifying the genetic defects of O-glycan biosynthesis by using electrophoresis (isoelectric focusing) in 2003. 15 In 2012, we introduced matrix-assisted laser desorption/ionization (MALDI) MS to the O-glycoform profiling of apoCIII.…”

“…The full glycoform is composed of GalNAc attached to Thr, and one galactose (Gal) and two N ‐acetylneuraminic acids (NeuAc or sialic acids), namely, NeuAc2,3Gal1,3(NeuAc2,6)GalNAc1‐ O ‐Thr. Furthermore, apoCIII with GalGalNAc (T‐antigen, Core1) and NeuAcGalGalNAc (Sia3Core1) or Gal (NeuAc)GalNAc (SIa6Core1), and unglycosylated apoCIII is also present 12–14 . ApoCIII was first analyzed for the purpose of identifying the genetic defects of O ‐glycan biosynthesis by using electrophoresis (isoelectric focusing) in 2003 15 .…”