Formaldehyde and ammonia as precursors to prebiotic amino acids.

Fig. 3. Inhibition of binding of ['4C]pentobarbital to rabbit antiserum by nonradioactive pentobarbital in buffered saline (0 0 *), plasma (0 O), or urine (X X). Incubation medium consisted of 0.10 ml of normal rabbit serum, 0.10 nml of rabbit antiserum (0.4 mg of protein), 0.01 ml of ['4C]pentobarbital (O.1 nmole), and 0.01 ml of either standard unlabeled pentobarbital (1 to 100 ng) or unknown sample and sufficient phosphatebuffered saline (O.O1M phosphate, pH 7.4) to make a final volume of 0.50 ml. Lines of regression were calculated by the method of least squares.