15N-Labeled Full-Length Apolipoprotein E4 as an Internal Standard for Mass Spectrometry Quantification of Apolipoprotein E Isoforms
Meiyao M. Wang, Illarion V. Turko
Apolipoprotein E isoforms (apoE2, apoE3, and apoE4) strongly affect the likelihood of developing Alzheimers disease (AD) with apoE4 being a major risk factor. However, the underlying mechanisms remain to be determined. These apoE isoforms vary by a single amino acid change and it is a challenge to distinguish them on protein level in in vivo experiments. We developed a mass spectrometry-based quantitative method utilizing 15N-labeled full-length apoE4 (15N-apoE4) as internal standard to quantify concentrations of specific apoE4 and total apoE and applied it to analysis of control and severe AD samples from human postmortem brain. In combination with known apoE genotype, this method provides concentrations of all three apoE isoforms for 5 out of 6 possible human apoE genotypes, ε2/ε2, ε2/ε4, ε3/ε3, ε3/ε4, and ε4/ε4. The measurements are performed on tissue samples in a single experimental run and used a single internal standard, 15N-apoE4. It is expected that this method will be applicable to quantification of specific apoE isoforms in the pathogenesis of various neurodegenerative diseases.
and Turko, I.
15N-Labeled Full-Length Apolipoprotein E4 as an Internal Standard for Mass Spectrometry Quantification of Apolipoprotein E Isoforms, Analytical Chemistry, [online], https://doi.org/10.1021/ac3018873
(Accessed December 11, 2023)