EXPRESSION IN ESCHERICHIA-COLI, PURIFICATION AND CHARACTERIZATION OF HEPARINASE-I FROM FLAVOBACTERIUM-HEPARINUM

The use of heparin for extracorporeal therapies has been problematical due to haemorrhagic complications; as a consequence, heparinase I fro m Flavobacterium heparimum is used for the determination of plasma hep arin and for elimination of heparin from circulation. Here we report t he expression of recombinant heparinase I in Escherichia coli, purific ation to homogeneity and characterization of the purified enzyme. Hepa rinase I was expressed with an N-terminal histidine tag. The enzyme wa s insoluble and inactive, but could be refolded, and was purified to h omogeneity by nickel-chelate chromatography. The cumulative yield was 43 %, and the recovery of purified heparinase I was 14.4 mg/l of cultu re, The N-terminal sequence and the molecular mass as analysed by matr ix-assisted laser desorption MS were consistent with predictions from the heparinase I gene structure. The reverse-phase HPLC profile of the tryptic digest, the Michaelis-Menten constant K-m (47 mu g/ml) and th e specific activity (117 units/mg) of purified recombinant heparinase I were similar to those of the native enzyme. Degradation of heparin b y heparinase I results in a characteristic product distribution, which is different from those obtained by degradation with heparinase II or III from F. heparimum. We developed a rapid anion-exchange HPLC metho d to separate the products of enzymic heparin degradation, using POROS perfusion chromatography media. Separation of characteristic di-, tet ra- and hexasaccharide products is performed in 10 min. These methods for the expression, purification and analysis of recombinant heparinas e I may facilitate further development of heparinase I-based medical t herapies as well as further investigation of the structures of heparin and heparan sulphate and their role in the extracellular matrix.