Cloning and Expression of Heparinase Gene from a Novel Strain Raoultella NX-TZ-3-15.

Heparin is a class of highly sulfated, acidic, linear, and complex polysaccharide that belongs to the heparin/heparan sulfate (HS) glycosaminoglycans family. Enzymatic depolymerization of heparin by heparinases is a promising strategy for the production of ultra-low molecular weight heparins (ULMWHs) as anticoagulants. In the present study, a novel heparinase-producing strain Raoultella NX-TZ-3-15 was isolated and identified from soil samples. Herein, the heparinase gene MBP-H1 was cloned to the pBENT vector to enable expression in Escherichia coli. The optimized conditions made the activity of recombinant heparinase reach the highest level (2140 U/L). The overexpressed MBP-H1 was purified by affinity chromatography and a purity of more than 90% was obtained. The condition for biocatalysis was also optimized and three metal ions Ca2+, Co2+, and Mg2+ were utilized to activate the reaction. In addition, the kinetics regarding the new fusion heparinase was also determined with a Vm value of 11.29 μmol/min and a Km value of 31.2 μmol/L. In short, due to excellent Km and Vmax, the recombinant enzyme has great potential to be used in the clinic in medicine and industrial production of low or ultra-low molecule weight heparin.