Further evidence of tautomerism in chromatograms of indolyl-3-pyruvic acid.

Evidence for the presence of serine and ethanolamine in SEP isolated from earthworms was presented previously (Rosenberg & Ennor, 1959). The present isolation of SEP in amounts sufficient to permit crystallization and chemical and physical analysis has also permitted comparison with D-SEP obtained by synthetic routes involving the use of D-serine. The results leave no doubt about the structure of the isolated material and provide proof of the presence of serine with the Dconfiguration in the molecule. The yield of SEP (300 mg. from 9-6 kg. of earthworms), although small, is nevertheless believed to represent the bulk of that present in the starting material, for no loss of ninhydrin-reacting components containing SEP was detected throughout the fractionation procedures. The yield corresponds to 3-1 mg./100 g. and contrasts with the minimal content of 50 mg./100 g. reported by Roberts & Lowe (1954) in river-turtle tissue. It has been suggested that SEP may be the precursor of lombricine (Ennor & Morrison, 1958; Rosenberg & Ennor, 1959), and the present results indicating the presence of D-serine in SEP (also present in lombricine: Beatty et al. 1959) are consistent with this hypothesis. The procedure developed for the isolation of SEP has yielded lombricine as a 'by-product' in amounts (1 g./kg.) appreciably larger than those reported earlier and represents almost a complete recovery of this compound from earthworm tissue.