[Synthesis of new chromogenic substrates for aspartyl proteases]

A general method was developed for the synthesis of new chromogenic substrates of aspartyl proteases: Dnp-Ala-Xaa-Phe-Phe-Ala-Arg-NH2, where Xaa was Ala or Ser. The synthetic scheme involved both chemical and enzymic stages, the condensation of tripeptides in an organic medium by means of pepsin immobilized on Celite being among the latters. The influence of organic solvents, reaction time, and the composition and ionic strength of the buffers used in the reaction mixture and at the pepsin immobilization step on the efficacy of the pepsin-catalyzed synthesis was studied.