Domain Structure of the Major Allergen Ovomucoid by Solution NMR

Abstract

Domain Structure of the Major Allergen Ovomucoid by Solution NMRNatalie E. Stenzoski, Gugsa W. Gebriel, Bruce D. Ray, Horia I. PetracheThe interest in the ovomucoid protein is twofold. First it is a protein of interest for medical studies due to its potent allergen activity. Second, as a special variety of glycosylated protein (Kazal family), it allows us to explore the role of protein glycosylation for a particular or model case. Glycosylated proteins are commonly secreted by tissues as signaling agents. For example, the serpin family serine proteinase inhibitor, α-1 proteinase inhibitor (A1AT/ α-1 antitrypsin) regulates trypsin. Recent research in our laboratory indicates that A1AT interacts with lipid membranes and affects ionic currents through the membrane. In contrast, ovomucoids do not. This difference in membrane interaction is expected to have a structural cause. However, very little overall structural data is available. The nature, location, and orientation of the glycosyl groups are determining factors in protein-membrane interactions and are deeply involved biological effects of glycosylated proteins, including effects on ion transport. We use solution NMR spectroscopy to determine the structure of the chicken ovomucoid protein, taking advantage of the division of its structure into three stable domains of 55-65 amino acids each. We present results on the protein purification steps and isolation of separate domains and the models of individual domains and overall protein structure from the analysis of NMR spectra.