Table 1.
In-house characterisation of GIP peptides by HPLC and MALDI-ToF MS.
| Peptides | Name | Sequence | % HPLC purity | Theoretical Mass (Da) |
Experimental Mass (Da) |
|---|---|---|---|---|---|
| 1 | hGIP(1-42) | YAEGTFISDYSIAMDKIHQQDFVNWLLAQKGKKNDWKHNITQ | 98.2 | 4983.6 | 4982.8 |
| 2 | hGIP(1-30) | YAEGTFISDYSIAMDKIHQQDFVNWLLAQK-NH2 | 98.7 | 3531.9 | 3530.6 |
| 3 | mGIP(1-30) | YAEGTFISDYSIAMDKIRQQDFVNWLLAQR-NH2 | 97.5 | 3579.0 | 3578.4 |
| 4 | hGIP(3-30) | EGTFISDYSIAMDKIHQQDFVNWLLAQK-NH2 | 96.7 | 3297.7 | 3296.3 |
| 5 | mGIP(3-30) | EGTFISDYSIAMDKIRQQDFVNWLLAQR-NH2 | 96.9 | 3344.7 | 3342.5 |
| 6 | h(Pro3)GIP(3-30) | PGTFISDYSIAMDKIHQQDFVNWLLAQK-NH2 | 98.5 | 3265.7 | 3263.4 |
| 7 | hGIP(3-42) | EGTFISDYSIAMDKIHQQDFVNWLLAQKGKKNDWKHNITQ | 98.3 | 4749.3 | 4749.2 |
| 8 | hGIP(5-30) | TFISDYSIAMDKIHQQDFVNWLLAQK-NH2 | 99.0 | 3111.5 | 3110.2 |
| 9 | hGIP(5-42) | TFISDYSIAMDKIHQQDFVNWLLAQKGKKNDWKHNITQ | 97.4 | 4563.1 | 4562.3 |
Amino acid sequence of peptides using one letter amino acid nomenclature. Differences in the mouse sequence compared with the human GIP sequence are highlighted by underlined bold text. HPLC was performed on a Phenomenex Aeris Peptide 3.6 µ XB-C18 250*15 mm HPLC column equilibrated with 0.12% trifluoroacetic acid (TFA)/H2O at a rate of 6 mL/min using 0.1% TFA in 70% acetonitrile/H2O on a Surveyor Plus Liquid Chromatography/HPLC system (Thermo Finnigan, California, USA). Absorbance was measured at 214 nm and purity determined from peak areas. Peptide molecular mass was confirmed using MALDI-ToF on a Voyager-DE BioSpectrometry Workstation. Abbreviations: GIP, glucose-dependent insulinotropic polypeptide; HPLC, high-performance liquid chromatography; MALDI-ToF MS, matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry; hGIP, human glucose-dependent insulinotropic polypeptide; mGIP, mouse glucose-dependent insulinotropic polypeptide.