Quantitative Analytical Method for Determining the
Levels of Gastric Inhibitory Polypeptides GIP<sub>1–42</sub> and GIP<sub>3–42</sub> in Human Plasma Using LC–MS/MS/MS
Atsushi Miyachi
Takayo Murase
Yuichiro Yamada
Takeshi Osonoi
Ken-ichi Harada
10.1021/pr400069f.s004
https://acs.figshare.com/articles/journal_contribution/Quantitative_Analytical_Method_for_Determining_the_Levels_of_Gastric_Inhibitory_Polypeptides_GIP_sub_1_42_sub_and_GIP_sub_3_42_sub_in_Human_Plasma_Using_LC_MS_MS_MS/2408656
Gastric inhibitory polypeptide (GIP),
an incretin, is an important
subject in endocrinology. Some LC–MS assays have been proposed;
however, their sensitivities are insufficient for the study of endogenous
human incretin. Here, we describe a nanoflow LC hybrid triple quadrupole/linear
ion trap MS assay for the simultaneous quantification of GIP<sub>1–42</sub> and GIP<sub>3–42</sub> from human plasma. We selected the
surrogate peptide to avoid oxidative modification, and the endoproteinase
Asp-N was selected for the proteolysis of GIP<sub>1–42</sub> and GIP<sub>3–42</sub>. The phenylalanine residue at position
6 in both GIP<sub>1–42</sub> and GIP<sub>3–42</sub> was
substituted with <sup>13</sup>C<sub>9</sub>,<sup>15</sup>N-labeled
phenylalanine, and these substituted GIPs were used as the internal
standards. This facilitated accurate and precise quantification because
large corrections are possible at all steps of sample pretreatment
and ionization efficiency. The lower limit of quantification was 1
pM for GIP<sub>1–42</sub> and 10 pM for GIP<sub>3–42</sub> by using 200 μL of plasma. Quantification of GIP<sub>1–42</sub> and GIP<sub>3–42</sub> in plasma from patients with type
2 diabetes was possible using this method, which included protein
precipitation, Asp-N proteolysis, solid-phase extraction, nanoflow
LC, and positive-ion multiple reaction monitoring cubed (MRM<sup>3</sup>) for GIP<sub>1–8</sub>, and MRM for GIP<sub>3–8</sub> to achieve accurate, precise, and quantitative analysis that can
be validated to support large clinical trials.
2013-06-07 00:00:00
GIP
MRM
Quantitative Analytical Method
type 2 diabetes
MS
nanoflow LC
200 μ L