Abstract
Among 10 antibiotics tested, cephaloridine and cephalothin showed the greatest inhibition of proline active transport. Ethylenediaminetetraacetate pretreatment of the cells did not enhance inhibition by any of these 10 antibiotics. The inhibition of active transport of 10 additional amino acids by cephaloridine and cephalothin was studied. Both antibiotics inhibited transport of three amino acids which, like proline, have transport systems resistant to osmotic shock; neither antibiotic inhibited transport of the remaining amino acids, including three with shock-resistant and four with shock-sensitive systems.