The amide, tyrosine and tryptophan contents and the sulphur distributions (cystine plus cysteine and methionine contents), of some plant leaf protein preparations

Abstract

Partial analyses have been made of protein preparations from the leaves of Dactylis glomerata, Phalaris tuberosa, Lolium perenne, L. italicum, Poa trivialis, Festuca rubra var. fallax (Hack) and Cynosurus cristatus, of the Graminae; Medicago sativa, Trifolium repens, T. pratense and Phaseolus vulgaris, of the Leguminosae; and Atriplex nummularium and Spinacia oleracea, of the Cheno-podiaceae. In comparison with the Graminae preparations, those of the Leguminosae and Chenopodiaceae were generally of slightly higher tyrosine contents, those of the Leguminosae of rather lower cystine (and/or cysteine) and methionine contents, and those of the Chenopodiaceae of rather higher amide contents. The ranges over all the prepns. were: 4.7-5.98% amide-N, 2.09-2.74% tyrosine-N, 1.43-1.98% tryptophan-N, 0.99-1.70% cystine (plus cysteine)-N, and 1.01-1.69% methionine-N, the lower limits in the last 2 cases probably being underestimations, and the upper limits being possibly too high owing to lack of specificity in estimation in these same cases.