title: Characterization of Peptide Polymer Interactions in Poly(alkylcyanoacrylate) Nanoparticles: A Mass Spectrometric Approach.
abstract: Drug/polymer interactions occur during in situ polymerization of poly(alkylcyanoacrylate) (PACA) formulations. We have used MALDI ionization coupled tandem time-of-flight (TOF) mass spectrometry as an accurate method to characterize covalent peptide/polymer interactions of PACA nanoparticles with the bioactives D-Lys6-GnRH, insulin, [Asn1-Val5]-angiotensin II, and fragments of insulin-like growth factor 1 (IGF-1 (1-3)) and human adrenocorticotropic hormone (h-ACTH, (18-39)) at the molecular level. Covalent interactions of peptide with alkylcyanoacrylate were identified for D-Lys6-GnRH, [Asn1-Val5]-angiotensin II and IGF-1 (1-3). D-Lys6-GnRH and [Asn1-Val5]-angiotensin II were modified at their histidine side chain within the peptide, whilst IGF-1 (1-3) was modified at the C-terminal glutamic acid residue. The more complex protein insulin was not modified despite the presence of 2 histidine residues. This might be explained by the engagement of histidine residues in the folding and sterical arrangement of insulin under polymerization conditions. As expected, h-ACTH (18-39) that does not contain histidine residues did not interfere in the polymerization process. Lowering the pH did not prevent the covalent association of PACA with D-Lys6-GnRH or IGF-1 (1-3). Conclusively, protein and peptide bioactives are potentially reactive towards alkylcyanoacrylate monomers via various mechanisms with limited interference of pH. Histidines and C-terminal glutamic acid residues have been identified as potential sites of interaction. The likelihood of their engagement in the polymerization process (initiators), however, seems dependent on their sterical availability. The reactivity of nucleophilic functional groups should always be considered and bioactives examined for their potential to covalently interfere with alkylcyanoacrylate monomers, especially when designing PACA delivery systems for protein and peptide biopharmaceuticals.
authors.forename: Alexandra P
authors.initials: AP
authors.lastname: Kafka
authors.forename: Torsten
authors.initials: T
authors.lastname: Kleffmann
authors.forename: Thomas
authors.initials: T
authors.lastname: Rades
authors.affiliation: University of Otago, School of Pharmacy, 18 Frederick Street, P.O. Box 56, 9054 Dunedin, New Zealand. arlene.mcdowell@otago.ac.nz.
authors.forename: Arlene
authors.initials: A
authors.lastname: McDowell
mesh_terms: D000804:Angiotensin II / Q000031:analogs & derivatives / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D053497:Corticotropin-Like Intermediate Lobe Peptide / Q000737:chemistry; D003487:Cyanoacrylates / Q000737:chemistry*; D004337:Drug Carriers; D004659:Enbucrilate / Q000737:chemistry; D018698:Glutamic Acid; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives / Q000737:chemistry; D006639:Histidine; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000737:chemistry; D007334:Insulin-Like Growth Factor I / Q000737:chemistry; D008958:Models, Molecular; D053758:Nanoparticles; D036103:Nanotechnology / Q000379:methods*; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D003487:Cyanoacrylates; D004337:Drug Carriers; D007328:Insulin; D010455:Peptides; C101568:angiotensin II, Asn(1)-Val(5)-; C558475:poly(ethylcyanoacrylate); D000804:Angiotensin II; D007987:Gonadotropin-Releasing Hormone; D018698:Glutamic Acid; D006639:Histidine; D053497:Corticotropin-Like Intermediate Lobe Peptide; D007334:Insulin-Like Growth Factor I; D004659:Enbucrilate