ISSN:
1432-0614
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
Abstract The Ser-170 residue of a trypsin-like enzyme from Streptomyces fradiae (SFT), which is considered to be the active-site serine, was replaced with alanine by site-directed mutagenesis to improve the affinity chromatography step for a Kazal-type trypsin inhibitor, pancreatic secretory trypsin inhibitor (PSTI). The resulting mutant SFT, designated as [S170A]SFT, was expressed in Streptomyces lividans and purified to homogeneity. [S170A]SFT was catalytically inactive, but still had the ability to bind tightly to PSTI and to soybean trypsin inhibitor with dissociation constants of 3.1×10-7 M and 1.9×10-8 M respectively. We further demonstrated that recombinant human PSTI secreted into Saccharomyces cerevisiae culture broth could be purified to homogeneity with a one-step [S170A]SFT-affinity column. The purified PSTI contained no molecules intramolecularly cleaved by active trypsin, which are found when trypsin-affinity chromatography is used for the purification. This eliminated the need for further separation of intact PSTI from intramolecularly cleaved PSTI by high-performance liquid chromatography, thus simplifying and improving its purification process.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002530050777
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