Oriental Yeast Co., Ltd.

Nobuyoshi Ishii

Yasuo Suzuki

Yushi Matuo

Kohji Uchida

Hideo Tanaka

The present invention provides a process for producing biologically active recombinant yeast protein disulfide isomerase, which includes the steps of: a) deleting, substituting, or adding one or more bases in a region encoding an endoplasmic reticulum retention signal in a gene encoding protein disulfide isomerase of yeast to modify the gene so as not to encode part or all of the endoplasmic reticulum retention signal; b) incorporating the modified gene into an expression vector; c) transforming host cells with the expression vector; and d) culturing the host cells transformed with the expression vector in a culture medium kept at a nearly neutral pH, thereby causing protein disulfide isomerase to be secreted in an active state outside the host cells. According to the process of the invention, recombinant yeast protein disulfide isomerase can be secreted in a large amount in a biologically active state into a culture medium, and can be collected by a simple purification method.

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Tokyo, Japan

Nobuyoshi Ishii