摘要：

Procedures are described for the production and purification of C-14-labelled peptides of mixed composition, derived from phytomass. Barley seeds (Hordeum vulgare) were germinated and grown in the dark for 6 days. On day 7, the seedlings were exposed to light in a (CO2)-C-14 atmosphere for 24 h. The plant leaves were harvested and their water-soluble C-14-labelled proteins extracted. These C-14-proteins were partially digested by sequential incubation with pepsin, alpha-chymotrypsin and trypsin. The resulting C-14-labelled peptides were separated from contaminating amino acids by elution from columns of copper-Chelex resin, and finally fractionated by gel-filtration chromatography and assigned to groups according to molecular size. The purified C-14-peptides ranged in relative molecular mass up to approximately 5,000, possessed a purity in excess of 97%, and were radiolabelled in all amino acid residues with an average specific radioactivity of 450 Bq/mu-mol. The methods described can bc readily adapted to produce not only mixed C-14-labelled peptides of any required attribute, such as molecular size or ionic charge, but also mixed C-14-proteins or C-14-amino acids.

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