The uptake of amino acids by carrot slices

Abstract

Conditions determining uptake of amino acids by slices of carrot have been investigated. Slices of carrot take up amino acids from the medium and establish a large concentration gradient in favor of the tissue. The process of uptake of both D- and L-isomers is inhibited by 2,4-dinitrophenol and by cyanide. The process, therefore, requires energy from respiration. The rate of uptake of L-histidine was greater than that of D-histidine, although for phenylalanine, valine and leucine there was usually no significant difference between amounts of the optical isomers taken up during 5 hr. The inorganic salts potassium chloride and potassium phosphate (solutions at pH 6.0-8.0) inhibited uptake of L-histidine. L-histidine and L-arginine mutually inhibit the uptake of each other.