The Amino-Acids of Grass Pollen

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SUMMARY Pollens collected from nine grass species were analysed for ammonia, urea, glutamine, asparagine, amino-nitrogen, total soluble nitrogen, and total nitrogen. Four grass pollens were also assayed microbiologically for 17 individual amino acids. Wide variations in composition were found between pollens from different grasses. Soluble nitrogen was in most cases relatively high in proportion to the total nitrogen. Asparagine occurred in much greater amount than glutamine. Of the free amino-acids, the most abundant was proline, its content in the perennial ryegrass pollen reaching 1-65 per cent, of the dry weight of the pollen The chemical composition of pollen is of great interest, not only because of the important part pollen plays in the reproductive process, but also because of the influence of many pollens, particularly grass pollens, on the incidence of hay fever. Particular attention has been paid to the skin-reactive fraction, which has been found to be largely protein or protein-carbohydrate (Robbins, Samuels, and Mosco, 1948). Detailed analysis of the nitrogenous constituents of pollen include those of Ray Sarker et al. (1949), who measured by microbiological assay the con centration of 12 amino-acids in hydrolysed sweet corn pollen. The amino acids estimated would therefore include those present in the free state as well as those present in bound forms including peptides and proteins. A qualitative analysis of amino-acids was performed by Auclair and Jamieson (1948), using two-way paper chromatography. They prepared alcohol extracts and also hydrolysates of the alcohol-insoluble residue of dandelion, willow, and mixed pollen, all the pollens being collected by bees. They found up to 22 amino-acids, with considerable variation between species, ^-alanine and a-aminobutyric acid were sometimes present. The purpose of the present investigation was to obtain quantitative infor mation on the soluble amino-acids, both free and bound, of some grass