ISONITRILE DERIVATIVES OF POLYACRYLAMIDE AS SUPPORTS FOR THE IMMOBILIZATION OF BIOMOLECULES

Isonitrile derivatives of crosslinked polyacrylamide beads (Biogell P-100) were prepared by a two-step procedure: a. N-hydroxymethylation (methylolation) of amide groups on the polymer by treatment with formaldehyde; and b. Attachment of side chains, containing isonitrile functional groups by a displacement reaction involving 1-tosyloxy-3-isocyanopropane (p-CH3-C6H4.SO2.O.(CH2)3 NC) and alkoxide ions generated on methylolated polyacrylamide by treatment with a strong base in a polar aprotic solvent. The modified polyacrylamide beads were tested as support for the immobilization of proteins, and low mol wt ligands by four component condensation (4CC) reactions. Trypsin-polyacrylamide acting on N-benzoyl-L-arginine ethylester exhibited nonlinear Michaelis Menten kinetics and distorted pH activity profiles. The kinetic anomalies could be reduced by increasing the concentration of buffer. The data were consistent with a model assuming ''buffer facilitated proton transport'' in a diffusionally constrained system.