DISTRIBUTION OF SELENOMETHYLSELENOCYSTEINE AND SOME OTHER AMINO ACIDS IN SPECIES OF ASTRAGALUS WITH SPECIAL REFERENCE TO THEIR DISTRIBUTION DURING GROWTH OF A BISULCATUS

Studies of the distribution of selenomethylselenocysteine and glutamylselenomethylselenocysteine in Astragalus bisulcatus indicate that the free amino acid is the principal seleno amino acid in vegetative parts, whereas the seeds are richer in the glutamyl peptide. Examination of the plants at different stages of growth has shown that during germination the peptide is probably hydrolyzed to free Se-methylselenocysteine which is present in 1-week-old seedlings in larger quantities than the peptide. The quantity of the peptide further declines as the seedlings grow so that in 1-month-old plants the amino acid bound selenium is present primarily as free Se-methylselenocysteine. The dipeptide reappears only in maturing pods, and it is suggested that this may be the time in the life of A. bisulcatus when it is synthesized. Sulphur analogues of the above compounds are also present in this plant and have a remarkably similar pattern of distribution. All four compounds are absent from the seeds of selenium non-indicator species of Astragalus. © 1970.