Globulins, plasma definition

In the blood plasma of mammals there is present a -pseudo-globulin called transferrin or siderophilin, and which at a definite point in its molecule forms an iron complex. This protein, whose molecular weight is in the region of 90,000, makes up about 3% by weight of the plasma proteins. The iron is complexed by it in the ferric form and only in the presence of COg. When the level of iron in the plasma is at its normal value, which in man is 129y/100 ml., the transferrin is saturated to the extent of 30% of the maximum amount of iron which it can carry. The same protein can also fix copper. 

In considering plasma as protein food its metabolism when injected intravenously must necessarily be compared with the behavior of the same protein when taken by mouth, inasmuch as there is such a difference in the mechanisms involved. Study of the nutritional value of plasma protein when given by mouth has resulted in a variety of results. For example, it has been shown (52) that following oral administration positive balance can be achieved in dop with precipitated washed bovine serum at a level comparable to that of casein. This same worker (53) as well as others (77, 80) has shown that beef serum by mouth is of high nutritional value in respect to plasma protein regeneration in protein depleted dop. On the other hand, powth experiments with human plasma have definitely shown nutritional deficiencies (10, 37) which are confined to the albumin fraction. By contrast, globulin and fibrin are of high nutritive value. The deficiency in albumin apparently is due to a lack of isoleucine and tryptophan this was shown not only... 

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