title: Interactions of alpha1-proteinase inhibitor with small ligands of therapeutic potential: binding with retinoic acid.
abstract: Human alpha(1)-proteinase inhibitor (alpha(1)-PI), also known as alpha(1)-antitrypsin, is the most abundant plasma serine protease inhibitor (serpin). It is best recognized for inhibition of neutrophil elastase. The alpha(1)-PI interactions with non-protease ligands were investigated mainly in regards to those molecules that may block the aggregation of alpha(1)-PI Z mutant. The objective of this study was to evaluate the potential of alpha(1)-PI to bind small non-peptide ligands of pharmaceutical interest that may attain additional properties to currently available alpha(1)-PI therapeutic preparations. Among putative ligands of bio-medical interest examined in this study, all-trans retinoic acid (RA) was selected due to its recently proposed roles in the lungs, and as an efficient optical probe. The results of this study, including absorption spectroscopy data, fluorescence quenching and the protein-induced chirality of the visible circular dichroism strongly suggest that alpha(1)-PI does bind RA in vitro to non-covalent complexes of up to two moles of RA per one mole of the protein. To our knowledge, this is the first report that provides experimental evidence of the alpha(1)-PI potential towards bi-functional drugs via a combination with RA, or potentially other molecules of pharmaceutical interest, that ultimately, may enhance currently available alpha(1)-PI therapies.
authors.affiliation: Laboratory of Biochemistry and Vascular Biology, Division of Hematology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA. elena.karnaukhova@fda.hhs.gov
authors.forename: Elena
authors.initials: E
authors.lastname: Karnaukhova
mesh_terms: D002942:Circular Dichroism; D015195:Drug Design; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007700:Kinetics; D008024:Ligands; D050505:Mutant Proteins / Q000378:metabolism; D010196:Pancreatic Elastase / Q000378:metabolism; D011485:Protein Binding; D015842:Serine Proteinase Inhibitors / Q000737:chemistry / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D017186:Titrimetry; D014212:Tretinoin / Q000737:chemistry / Q000378:metabolism*; D014357:Trypsin / Q000378:metabolism; D000515:alpha 1-Antitrypsin / Q000737:chemistry / Q000378:metabolism*
chemical_list: D008024:Ligands; D050505:Mutant Proteins; D015842:Serine Proteinase Inhibitors; D000515:alpha 1-Antitrypsin; D014212:Tretinoin; D010196:Pancreatic Elastase; D014357:Trypsin