The open structure of the biocompatible polyethylene glycol polyamide copolymer (PEGA resin) is presented in Fig. 1 , exemplified by the application of the commercially available bis-2-aminopropyl-PEG₁₉₀₀. With the use of this PEG₁₉₀₀, permeability with proteins up to 50 kDa has been achieved, as demonstrated by gel permeation chromatography (1). A resin-bound fluoroescencequenched peptide substrate showed 80% cleavage with subtihsin Carlsberg (MW 27 kDa) in 1 h and the cleavage went to completion in ∼2 h. The resin could also be used for glycopeptide assembly using bovine β-(1→4)-galactosyl transferase (MW 43/49 kDa) to transfer galactose to the 4-position of GlcNAc (2) In this example, the diffusion and reorientation of the enzyme inside the polymer network was a rate-limiting factor for the reaction, which could, however, be brought to completion in 72 h This indicates that the reaction was performed at the practical limit of protein size for preparative enzyme reactions in this resin. PEGA resins perform excellently in solid-phase assays of biomolecular reactions. Furthermore, they are transparent and no light is absorbed above 250 nm, so they can be used with a variety of different chromophores and fluorescent probes for detection of biomolecular reactions.

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