A simplified spectrophotometric determination of ester groups in lipids.

Fig. I is a rad ioautograph of the ionogram. The free phospha te b a n d has been allowed to run off the anode end of the paper. The exac t correspondence of the radioact ive bands from the three diisopropyl phosphory l -enzymes indicates tha t the hydro lysa tes contain identical pept ides of phosphoserine which are ent i re ly different from those der ived from ovalbumikx. The s t ruc ture of the different peptid~" bands is not certain at present bu t is under investigation, F r o m the n u m b e r present arid their iden t i ty in the three enzymes it is p robab ly safe to conchtde tha t elastase, like t rypsi t l and chymot ryps in contains the sequence G l y . A s p S e r ( ; l y a round its reac t ive serinc residue. B . S . HARTLEX" Dvpartmcnt o/Biochemistry, ~.Miversity o/Cambridge M . A . NAL'¢;HTON (Great Britah~) F. SA.~G~R"