Arginine metabolism by pumpkin seedlings. Separation of plant extracts by ion exchange resins

Arginine-U-¹⁴C was injected into the cotyledons of 7-day oldpumpkin seedlings. At most, 24% of the administered ¹⁴C wastransported to the axis tissue. The amounts of arginine incorporatedinto cotyledonary protein suggests that turnover was occurringat a rapid rate. Arginine was extensively metabolized, and after96 hr 50% of the administered ¹⁴C had been released as ¹⁴CO₂.The remaining label was primarily in unmetabolized arginine,protein or transported to the axis tissue with little labelin other amino acids. The results suggest that the carbon fromarginine is incorporated into protein or catabolized to CO₂while the carbon for new amino acid skeletons is derived fromsugar. A simple, reproducible method for the quantitative fractionationof plant extracts or hydrolysates of insoluble plant materialinto basic amino acids, acidic amino acids, neutral amino acids,organic acids and sugars was reported. (Received September 10, 1968; )