US 5,496,719 A · Polypeptide from Humicola insolens possessing protein disulfide isomerase activity gene encoding the same

Abstract

A highly thermostable polypeptide possessing protein disulfide isomerase (PDI) activity, a gene coding for the polypeptide and a process for producing the polypeptide are provided. The polypeptide possessing PDI activity is characterized by A) having a capability of catalyzing a disulfide exchange in proteins, B) recognizing mainly ribonuclease A as a substrate, C) having a suitable active temperature of 20.degree. to 70.degree. C., D) being stable at a pH value of 6 to 9, and E) having a molecular weight of about 60,000 to 62,000. Since it has a higher thermostability and exhibits a stable activity in a wider dithiothreitol concentration range as compared with the conventional PDI, it is possible to provide a novel enzyme active protein which can be advantageously used for a refolding reaction of certain proteins. Further, a process which enables the polypeptide possessing PDI activity to be efficiently produced using Humicola insolens or a transformant transformed with an expression vector containing the above-described gene is also provided.

Claims2

Dependent claims

An isolated thermostable polypeptide of Humicola insolens KASI origin, possessing protein disulfide isomerase activity which catalyses a disulfide exchange in protein, and being characterized by the following properties:

A) it carries out disulfide exchange at least on ribonuclease A;
B) a suitable temperature for the enzyme to be active is 20.degree. to 70.degree. C.;
C) its residual activity after a treatment for 30 minutes at pH 7.5 is about 100% at a temperature between 30.degree. C. and 60.degree. C., more than 80% at a temperature of 70.degree. C., and more than 50% at a temperature of 80.degree. C., taking the activity before said treatment as 100%;
D) it is stable at a pH value of 6 to 9;
E) its residual activity after a treatment for 30 minutes at 30.degree. C. is more than 60% at pH 5, more than 80% at pH 6, more than 90% at pH of from 8 to 9, and more than 30% at pH 10, taking the activity before said treatment as 100%;
and
F) it has a molecular weight of about 60,000 to 62,000, as measured by SDS-polyacrylamide gel electrophoresis.

4 more elements

Dependencies are inferred from the claim text.

Polypeptide from Humicola insolens possessing protein disulfide isomerase activity gene encoding the same

Life of this patent

Polypeptide from Humicola insolens possessing protein disulfide isomerase activity gene encoding the same

Life of this patent

Abstract

Claims2