Enzyme immobilization on macroreticular polystyrene

Blocking of non-specific sorption in ELISA on formylated polystyrene beads

The effect of pH of the blocking solution on the non-specific sorption of peroxidase conjugates to the 0.63-cm formylated polystyrene beads was studied. Anti-G-HRP and BSA-HRP sorption was shown to dramatically depend on pH of blocking protein solutions and was minimum at pH=pI. Sorption of G-HRP weakly depended on pH of the blocking buffer. The blocking efficiency of proteins on unmodified beads, as well as of Tween-20 on formylated beads appeared to be pH independent. The optimized blocking step resulted in a multiple decrease in the non-specific sorption of conjugates on formylated beads.

Immobilization of manganese peroxidase from Lentinula edodes on alkylaminated Emphaze AB 1 polymer for generation of Mn3+ as an oxidizing agent

Manganese peroxidase (MnP) is secreted by white-rot fungi and participates in the degradation of lignin by these organisms. MnP uses H2O2 as an oxidant to oxidize MnII to MnIII as the manganic ion Mn3+. The Mn3+ stabilized by chelation, is a highly reactive nonspecific oxidant capable of oxidizing a variety of toxic organic compounds. Previous attempts at immobilization of MnP, purified from Lentinula edodes through reactive amino groups, have been hindered by the protein's low lysing content of only 1% and its instability above pH 6.0. As an alternative to amine coupling, the enzyme has now been covalently immobilized through its carboxyl groups, using an azlactone-functional copolymer derivatized with ethylenediamine and 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ) as a coupling reagent. The immobilization reaction was performed under acidic (pH 5.25) conditions, and 90% coupling efficiency was achieved within 2h. Net immobilization efficiencies, expressed as the product of protein coupling efficiency and enzyme activity, have been measured at > 95% within 4h. The MnP-NH-polymer and the free soluble protein were characterized and compared for their pH, temperature, and storage stabilities, as well as their H2O2 dependence and kinetics. The tethered MnP, employed in an immobilized enzyme bioreactor for generation of chelated Mn3+ may have industrial applications as a nonspecific oxidant of organopollutants.

Pulse injection analysis of the binding of serum proteins to porous polymer gels modified with formyl groups

Highly porous spherical polymer gels were modified with formyl groups by a modified Friedel-Crafts reaction and the interaction of serum proteins with the modified gels were examined by pulse injection analysis. The introduction of formyl groups into the polymer greatly increases its protein-binding capacity, and the protein bound to the gel is not eluted by washing with acid, alkali or urea solution. The effects of temperature and the percentage of formyl group substitution on the binding capacity indicate that the binding process can be interpreted as initial approach of the protein to the polymer surface, caused by the hydrophobic interaction, followed by formation of a stable Schiff base between the polymer gel and the protein. Theoretical treatment of the elution behaviour of the protein from the polymer-packed column is also examined, with the assumption that there are three kinds of binding site in the polymer gel: surface, macropore and micropore regions. These polymers are shown to be useful for the removal of proteins from biological samples in clinical assays using immobilized enzymes.