Enzymic and immunochemical properties of lysozyme: XI. Conformation and immunochemistry of the two-disulfide peptide and the role of the tryptophan and lysine residues in its antigenic reactivity

摘要: Abstract The previously described peptide 62–68 (Cys 64-Cys 80) 74–96 76-Cys 94) (Atassi, M. Z., Suliman, A. and Habeeb, F. S. (1975) Biochim. Biophys. Acta 405, 452–463), which accounted for about one-third of the total antigenic reactivity native lysozyme, was isolated here with lysine 97 attached to it. subjected specific modification reactions in order determine some residues formed part its reactive site. ORD measurements showed that greatly unfolded solution relative expected mode folding within intact lysozyme molecule. Modification two tryptophan by reaction 2,3-dioxo-5-indolinesulfonic acid provided a derivative possessed similar conformational parameters those unmodified peptide. However, retained only half immunochemical Succinylation amino groups afforded whose were identical but lost. followed succinylation resulted almost complete loss reactivity, not due differences. also destroyed on removal tryptophans 62 63, sequence 84–93 from loop 74–79 74–75 chymotryptic digestion. From these previous results it concluded site this molecule incorporates one or both 63 as well lysines 96 97. disulfides 64–80 76–94 bring parts into single intactness is essential maintenance