Phylogenesis of the general structure of immunoglobulins.

The study of the general structure of macroglobulins and 7S (IgG) immunoglobulins of frog and tortoise by relaxation methods shows the rotational correlation time of 7S immunoglobulins to be 67–68 nsec whereas that of macroglobulins of frog is 135 nsec and of tortoise is 103 nsec. Experimental values of rotational correlation time for 7S immunoglobulins are close to those calculated for the model of this molecule approximated by the rigid rotational ellipsoid and lower than those estimated for macroglobulins. This indicates that frog and tortoise 7S immunoglobulins have a fairly compact general structure with no marked intramolecular rotational freedom for high-molecular fragments, whereas macroglobulins possess it to a limited extent. It is seen from our evidence on the rigidity of 7S immunoglobulins and the limited flexibility of macroglobulins in amphibia and reptiles, as compared to previous data on the limited flexibility of carp macroglobulins and on the pronounced flexibility of IgG and IgM of mammals, that the general structure becomes more flexible on passing from lower vertebrates to representatives of a more recent class of mammals. The reported increased flexibility of immunoglobulins accompanied by the progressive evolution of species is likely to provide one of the first indications of the possible directed selection in the course of molecular evolution.     

Identification of N-acetylglucosamine-binding immunoglobulins in chicken egg yolk and serum distinct from the major mannose-binding immunoglobulins.

An N-acetyl-D-glucosamine (GlcNAc)-binding protein of 170 kDa has been isolated from hen serum and egg yolk. Another GlcNAc-binding protein of higher molecular mass was present only in the serum. The 170 kDa protein co-electrophoresed and co-chromatographed in gel filtration with a chicken IgG, and behaved identical to chicken IgG in double immunodiffusion with goat anti-chicken gamma chain antiserum. The sugar-binding hierarchy for the serum and yolk binding proteins, determined with bovine serum albumin neoglycoproteins, was GlcNAc greater than N-acetyl-D-galactosamine greater than glucose = galactose = L-fucose greater than mannose. This hierarchy was unlike any previously reported GlcNAc-binding proteins. The larger serum binding protein component was shown to be an IgM by double immunodiffusion with goat anti-chicken mu chain antiserum. The serum and yolk GlcNAc-binding proteins comprise a unique set of sugar-binding immunoglobulins distinct from the previously reported hen serum and yolk mannose-binding proteins (Wang et al., 1986).     

Placental transmission of thyroid-stimulating immunoglobulins.

Long-acting thyroid stimulator (LATS) and LATS protector (LATS-P) were assayed at or near delivery in serum from 18 pregnant women with a history of past or present thyrotoxicosis. The results suggested that neonatal thyrotoxicosis may be predicted prenatally if maternal serum LATS and LATS-P concentrations near delivery are above certain levels.