Abstract
Egg albumin, freed from the other proteins of egg white by repeated crystallization, produces typically the anaphylaxis reaction. It sensitizes in doses as small as one twenty-millionth of a gram, fatally in doses of one millionth of a gram. The minimum lethal dose for sensitized pigs is about one half a milligram by intraperitoneal injection, and about one tenth to one twentieth of a milligram when injected into the circulation. The unpurified proteins of egg white are much less active, the minimum sensitizing dose being about one hundred times greater and the minimum lethal dose being five times greater than with purified egg albumin. This suggests that inhibiting substances are possibly present in crude egg white.
The minuteness of the minimum sensitizing and intoxicating dose of pure protein seems to indicate conclusively that both the sensitizing and the intoxicating agent are one and the same kind of protein molecule, or else two different constituents of the same molecule.
Gelatin seems to be devoid of the power of participating in the anaphylaxis reaction, either with itself or with other proteins. This may be due to its poverty in aromatic radicals; it probably is not due to the heating that is necessary for the conversion of collagen into gelatin. Addition of tyrosin to gelatin (without chemical combination) does not modify gelatin in respect to the anaphylaxis reaction.
Milk does not lose its sensitizing or intoxicating power when heated to 100° for 30 minutes. If large enough doses of serum heated to the same degree are used they will sensitize guinea pigs to unheated serum. Coagulation with alcohol destroys or reduces grcatly the toxicity of proteins which it renders insoluble in water (egg albumin) but not proteins that it does not render insoluble (serum albumin).
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