Abstract: A chimeric protein is provided which comprises a target protein and has been designed so as to be easily cleaved by a processing enzyme, permitting a target protein to be efficiently recovered. The chimeric protein is represented by the following formula:A-L-Bwherein A represents a protective peptide;B represents a target peptide; andL represents a linker peptide having the sequence X.sub.1 -X.sub.2 -(Pro, Lys, or Arg)-Arg, wherein X.sub.1 and X.sub.2 represent any amino acid, in its C-terminal region and a domain rich in His in its N-terminal region.

Abstract: Kex2 protease derivatives obtained by transforming methanol-assimilating with expression vectors containing DNA coding for any amino acid sequence which is an amino acid sequence of Kex2 protease wherein the N-terminus is the Met at position 1 and the C-terminus is one of the amino acids between positions 618 (inclusive) and 698 (inclusive), or a modification of that amino acid sequence, culturing the resulting transformants and recovering the derivatives from the cultures, as well as gene systems coding for the derivatives and a method for producing the Kex2 protease derivatives using the gene systems. Also, a method for excision of desired peptides using the Kex2 protease derivatives.