Solution conformation of model polypeptides with the use of particle beam LC/FT-IR spectrometry and electrospray mass spectrometry.
Solution conformations of the polypeptides beta endorphin (beta-END) and a cysteine peptide (CYSP) were investigated with the use of particle beam LC/FT-IR spectrometry. Gradient elution HPLC with mobile phases that contained acetonitrile with 0.1% TFA (v/v) and 0.1% aqueous TFA (v/v) were used. The conformations of both polypeptides were studied in 0.9% sodium chloride injection USP, 5% dextrose in water injection USP and sterile water for injection USP. Additional conformational studies over a pH range of 2-10, temperatures of 25, 50, 75 and 100 degrees C and after storage for 24 h were investigated. The studies indicated that the two polypeptides did not behave similarly under identical conditions. It was observed that both beta-END and CYSP had slightly different conformations in the various parenteral solutions. It was also shown that the conformation of CYSP changed with both pH and temperature while beta-END was conformationally stable to both temperature and pH. The identity of the peptides and the conformationally sensitive charge-state intensities of the peptides were investigated with electrospray ionization mass spectrometry (ESI/MS). The combination of IR and MS data allowed an estimation of solution effects on the conformations of the model polypeptides.
Venkateshwaran
T G
TG
Department of Medicinal Chemistry, College of Pharmacy, University of Georgia, Athens 30602-2352, USA.
Stewart
J T
JT
de Haseth
J A
JA
Bartlett
M G
MG
D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013997:Time Factors; D001615:beta-Endorphin / Q000737:chemistry
D007202:Indicators and Reagents; D010446:Peptide Fragments; D010455:Peptides; D012996:Solutions; D001615:beta-Endorphin