Direct purification and immobilization of recombinant hyaluronan lyase from unclarified feedstock using immobilized metal affinity magnetite for oligo-hyaluronan preparation

Submicron-size magnetite with metal chelating capability was prepared to directly and specifically recover recombinant hyaluronan (HA) lyase from unclarified E. coli cells lysate. The unclarified contaminants did not have significant effect on reducing the yield and purity of the recovered 6xHis tagged HA lyase. The recombinant HA lyase recovered on this immobilized metal affinity magnetite (IMAM) (12.0 mg/g magnetite) was used as an immobilized enzyme to digest high molecular weight HA for the preparation of oligo-HA. Once immobilized, HA lyase activity decreased significantly to about 10% of its free activity. After an abrupt activity decrease in the first two batch reaction, 40% of the initial activity of IMAM immobilized HA lyase was maintained at the following three repeated batch reaction. The average size of the oligo-HA prepared was estimated to be about 1660 Da by using the unsaturated oligo-HA concentration measured at OD232. However, the average molar mass of oligo-HA determined by MALDI-TOF-MS was around 1400.