title: Engineering of Harobin for enhanced fibrinolytic activity obtained by random and site-directed mutagenesis.
abstract: We have previously published a report on the cloning and characterization of Harobin, a fibrinolytic serine protease. However, the broad application of this fibrinolytic enzyme is limited by its low expression level that was achieved in Pichia pastoris. To counteract this shortcoming, random and site-directed mutagenesis have been combined in order to improve functional expression and activity of Harobin. By screening 400 clones from random mutant libraries for enhanced fibrinolytic activity, two mutants were obtained: N111R, R230G. By performing site-directed mutagenesis, a Harobin double mutant, N111R/R230G, was constructed and can be functionally expressed at higher level than the wild type enzyme. In addition, it possessed much higher fibrinolytic and amidolytic activity than the wild type enzyme and other single mutants. The N111R/R230G expressed in basal salts medium was purified by a three step purification procedure. At pH of 6.0-9.0, and the temperature range of 40-90 °C, N111R/R230G was more active and more heat resistant. The fibrinolytic activities of Harobin mutants were completely inhibited by PMSF and SBTI, but not by EDTA, EGTA, DTT, indicating that Harobin is a serine protease. N111R/R230G showed much better anti-thrombosis effect than wild type Harobin and single mutants, and could significantly increase bleeding and clotting time. Intravenous injection of N111R/R230G in spontaneous hypertensive rats (SHR) led to a significant reduction in systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) (p < 0.01), while heart rate (HR) was not affected. The in vitro and in vivo results of the present study revealed that Harobin double mutant N111R/R230G is an appropriate candidate for biotechnological applications due to its high expression level and high activity in area of thrombosis and hypertension.
authors.affiliation: Department of Cell Biology, Institute of Biomedicine, College of Life Science and Technology, Jinan University, Guangzhou, Guangdong 510632, China.
authors.forename: Zhuojian
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Cell Biology, Institute of Biomedicine, College of Life Science and Technology, Jinan University, Guangzhou, Guangdong 510632, China.
authors.forename: Xiaojia
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Cell Biology, Institute of Biomedicine, College of Life Science and Technology, Jinan University, Guangzhou, Guangdong 510632, China.
authors.forename: Shujun
authors.initials: S
authors.lastname: Guo
authors.affiliation: Department of Cell Biology, Institute of Biomedicine, College of Life Science and Technology, Jinan University, Guangzhou, Guangdong 510632, China.
authors.forename: Huihua
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Cell Biology, Institute of Biomedicine, College of Life Science and Technology, Jinan University, Guangzhou, Guangdong 510632, China.
authors.forename: Haojun
authors.initials: H
authors.lastname: Dong
authors.affiliation: Department of Cell Biology, Institute of Biomedicine, College of Life Science and Technology, Jinan University, Guangzhou, Guangdong 510632, China.
authors.forename: Guoyi
authors.initials: G
authors.lastname: Wu
authors.affiliation: Department of Cell Biology, Institute of Biomedicine, College of Life Science and Technology, Jinan University, Guangzhou, Guangdong 510632, China. Electronic address: tha@jnu.edu.cn.
authors.forename: An
authors.initials: A
authors.lastname: Hong
authors.affiliation: National Key Laboratory of Protein Engineering and Plant Gene Engineering, LSC, Peking University, Beijing 100871, China. Electronic address: gj@pku.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Gu
mesh_terms: D000818:Animals; D004546:Elapid Venoms / Q000201:enzymology / Q000235:genetics*; D017815:Elapidae / Q000235:genetics* / Q000378:metabolism; D005342:Fibrinolysis / Q000187:drug effects*; D005343:Fibrinolytic Agents / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D016297:Mutagenesis, Site-Directed; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology; D057057:Serine Proteases / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology
chemical_list: D004546:Elapid Venoms; D005343:Fibrinolytic Agents; D011994:Recombinant Proteins; D057057:Serine Proteases
keywords: Double mutant; Harobin; Hypertension; Random mutagenesis; Thrombosis