Globulin, serum iodination

In all cases, the tubes were allowed to stand for 1 hour at room temperature, following which iodinated APS-314d (4000 cpm) was added in 0.05 ml of assay buffer to all tubes, as well as to 3 tubes labeled as total radioactivity . With the exception of the latter, the tubes were vortexed for a few seconds and then they received 0.05 ml of a mixture containing anti-beraprost serum (1 50,000 dilution) sheep anti-rabbit y-globulins (200 pl/ml) and rabbit y-globuhns (200 ig/ml) (the quantity of rabbit y globulins involved depends on the quality of the purihed sheep anti-rabbit y-globulins serum and must be checked with each preparation of this second antibody). 

Standard point Samples Human blank plasma Assay buffer Iodinated APS-314d Mixture containing rabbit anti-Beraprost serum, sheep anti-rabbit y-globulins and rabbit y-globulins... 

Kleczkowski (167) has indicated that in iodinated serum globulin the diiodotyrosine yields no color with the Folin s phenol reagent and that the color obtained arises from the tryptophan. This is surprising in view of the fact that pure diiodotyrosine produces at least 50% of the color of tyrosine. It is possible that in this instance the tyrosine has been oxidized as well as iodinated. The phenol color value of tyrosine oxidized by iodine is reported (70) as 20% or less of the original tyrosine. 

By means of the azide reaction N-carbobenzoxy 3,5 diiodothyronine was joined to horse serum globulin, albumin, and thyro-globulin (223). After iodination to form the thyroxyl compound anti sera to these, conjugated proteins were produced and the authors report that "passive immunization with anti sera to these derivatives protects against normal physiological effects of exogenously administered thyroglobulin and thyroxine. ... 

Although earlier workers iodinated proteins, Ostwald in 1910 provided the first unequivocal proof that tyrosine in proteins was iodinated. He isolated diiodotyrosine from iodinated albumin (273), gliadin (274), and casein (275)-. Since then papers on serum albumin, egg albunun, and serum globulin (276), pepsin (6, 7), insulin (125), and the lactogenic hormone (277) all indicate that the action of iodine on these proteins in neutral or slightly alkaline solution is one of substitution on the tyrosine residues. The reaction is as follows ... 

Whole serum was used for immuno-electrophoresis studies and measurement of serum thyroxine and protein-bound iodine but a crude -globulin preparation was obtained by ammonium sulphate precipitation (4) to Inject into mice for bioassay purposes this was... 

Radioactive tracer studies are well suited for zone electrophoresis because the components can be located, analytically determined, and investigated for radioactivity using the same strip (see Fig. 7). The rate of formation of the serum proteins has been studied by incorporation in vivo of valine C (Gros et al., 1952) and of methionine S (Niklas and Maurer, 1952). In vivo incorporation of P into serum has also been investigated with this technique the iodine was found to assemble in a nondialyzable fraction between albumin and ai-globulin in rabbit (Maurer and Teichenbach, 1952) and near a2-globulin in man (Larson et al., 1952). 

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