title: Chromatographic separation and mass spectrometric identification of positional isomers of polyethylene glycol-modified growth hormone-releasing factor (1-29).
abstract: A one-step chromatographic method capable of separating all isomers of polyethylene glycol (PEG)-growth hormone-releasing factor (GRF) (1-29) conjugates was developed. The unmodified GRF (1-29) and seven different isomers of PEG-GRF (1-29) conjugates were separated by using a simple reversed-phase HPLC method depending on the differences of hydrophobicity due to the number and site of PEG attachment. The PEGylation sites of all isomers of PEG-GRF (1-29) conjugates were identified by determining the molecular masses of the Lys-C digested fragments with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. This study is a first report for the separation of all PEG-conjugate isomers and would be useful for further studies to find the promising conjugate by evaluating biological activity and stability of each isomer.
authors.affiliation: Drug Targeting Laboratory, College of Pharmacy, SungKyunKwan University, 300 Chonchon-dong, Jangan-ku, Suwon City 440-746, South Korea.
authors.forename: Yu Seok
authors.initials: YS
authors.lastname: Youn
authors.forename: Dong Hee
authors.initials: DH
authors.lastname: Na
authors.forename: Sun Dong
authors.initials: SD
authors.lastname: Yoo
authors.forename: Soo-Chang
authors.initials: SC
authors.lastname: Song
authors.forename: Kang Choon
authors.initials: KC
authors.lastname: Lee
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D013007:Growth Hormone-Releasing Hormone / Q000737:chemistry*; D007536:Isomerism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D010446:Peptide Fragments; D011092:Polyethylene Glycols; D013007:Growth Hormone-Releasing Hormone; C059148:somatotropin releasing hormone (1-29)