Immunochemical Properties of Native and Denatured Horse Serum Globulins

Abstract

The problem of the relation of antibodies to normal serum globulins has been approached in the past by comparison of their chemical, physical, and immunological properties in the native state (cf. 1-3). Little information is available, however, on their relative behavior in the denatured state. This paper describes an investigation of the effects of denaturation by guanidine hydrochloride on certain physicochemical and immunological properties of Type I antipneumococcal horse serum globulin. In the fight of recent theories of the structure and synthesis of antibodies (4, 5) it appeared also of interest to determine whether denaturation of normal and immune globulin might accentuate or diminish the antigenic relations which exist between them in the native form.Comparative physicochemical properties of normal and immune serum globulins have been reviewed by Kabat (3). Wright (6) has reported that the antigenic nature of horse antibody proteins is essentially the same as that of horse normal gamma globulin. However, quantitative investigations by Treffers et al. (7)(8)(9) based on earlier findings of Ando et al. (10), and Marrack and Duff (11), revealed that antipneumococeal horse serum globulin differs from normal gamma globulin in its reaction with an antispecific precipitate rabbit serum. A high degree of cross-reactivity existed, and it was further noted that those antibodies that were precipitated by either antigen were incapable of differentiating between the two. These investigations provided experimental proof for earlier suggestions (12) that the groups on the antibody molecule responsible for antibody activity are unrelated to those involved in antigenic specificity.Previous work on the effects of denaturation on the serological and physicochemical behavior of immune globulins has been extensively reviewed (1,13,14). The observation that monolayers of Types i and III antipneumococcal rabbit globulin are serologic.ally active (15), suggests the independence of serological activity of a unique stereochemical configuration. However, in the light of a recent hypothesis (16) that formation of protein films involves the separation of preformed layers of peptide chains rather than unfolding into individual chains, a functional relation between intact two dimensional configurations and antibody activity is not excluded.