1. An individual from whom blood, tissue, or an organ is taken for transplantation. 2. A compound that will transfer an atom or a radical to an acceptor; e.g., methionine is a methyl d.; glutathione is a glutamyl d. 3. An atom that readily yields electrons to an acceptor; e.g., nitrogen, which will donate both electrons to a shared pool in forming a coordinate bond. [L. dono, pp. donatus, to donate, to give]
hydrogen d. a metabolite from which hydrogen is removed (by a dehydrogenase system) and transferred by a hydrogen carrier to another metabolite, which is thus reduced.
universal d. in blood grouping, a person belonging to group O; i.e., one whose erythrocytes do not contain either agglutinogen A or B and are, therefore, not agglutinated by plasma containing either of the ordinary isoagglutinins, alpha or beta.
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