Ai-globulins

Peptides Hypertensin ai-Globulin Renin Peptide Acute No Acute Yes... 

To achieve a proper balance between sensitivity and resolution, the amount of serum protein that is applied to an electrophoretic support must be optimum. Albumin is about 10 times more concentrated in serum than the smallest fraction, the ai-globulins. Therefore the amount of serum applied should prevent overloading with albumin but still be adequate to quantify arglobulin. For the separation of serum proteins using polyacrylamide gel electrophoresis (PAGE), 3(lL of serum containing approximately 210 pg of total... 

D2. Darcy, D. A., A rat ai-globulin associated with growth. Protides Bid. Fluids, Proc. Collog. 10, 131-133 (1963). 

Factor IX 57,000 ai Globulin Single polypep- 2 Subunits Serine protease... 

Normal plasma to which synthetic radiothyroxine of high activity had been added was similarly electrophoresed, and the position of the thyroxine on the paper strip compared with the positions of the natural hormone in the patients sera. Both were found to be associated with a protein having a mobility similar to that of ai-globulin. Triiodothyronine does not appear to be specifically associated with this protein in the circulation (Gross unpublished). 

Figure 2 Serum electrophoresis of a patient with a small monoclonal band (top) CE (bottom) agarose electrophoresis l = internal standard A = albumin ai =ai-globulin a2 = a2-glob-ulin, T = transferrin C = complement M = monoclonal band > = >-globulins X = marker). CE conditions capillary 30cmx 50 pm (ID), 9kV, detection at214nm. Separation buffer 7g boric acid, 7g sodium carbonate, and 5 g of polyethylene glycol 8000 in 1000 ml water.

The occurrence and composition of the glycoproteins in human blood serum have been reviewed by Winzler (5). Evidence for the existence of at least four such materials has been obtained by Schmid 79). One of these is present in serum to the extent of 0.5 % and is the principal glycoprotein of the ai-globulin fraction. 

Bilirubin resulting from the breakdown of haemoglobin in the cells of the reticulo-endothelial system passes into the blood plasma where it circulates in combination with the ai-globulin fraction from there it passes into the cells of the hepatic parenchyma which conjugate the bilirubin with glucuronic add and excrete the product in the bile. Furthermore the hepatic parenchyma is the site of considerable protein synthesis, that of the blood plasma proteins. 

An ai-globulin normally only found in detectable quantities in fetal serum. It is measured in two clinical situations ... 

In the plasma, bile pigment, heme and hemoglobin are not free but bound to specific proteins. Bilirubin and bilirubin di ucuronide are transported on serum dbumin and also on a specific ai-globulin (316) from R.E. cells of the body to the liver by way of the blood stream. Tlie blood in a human contains 0.2-0.8 mg total bilirubin per 100 ml plasma. 

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). 

Thorn et al. (353) made electrophoretic separations of the plasma proteins in seven cases of nephrosis, the fractionations being effected with veronal buffer at pH 8.6 to afford more complete separation of the ai- and a2-globulins. The results in five cases are reproduced in Table VI. The ai-globulin component was found to remain within substantially normal hmits whereas the refractive area of the 2-fraction was increased two- to almost fivefold, that of the j3-globulin component was two to three times normal, and fibrinogen about doubled. The albumins characteristically showed a marked reduction. The refractive area of the... 

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