Use of protein-acrylamide copolymer hydrogels for measuring protein concentration and activity

Anal Biochem. 2004 Jun 15;329(2):180-9. doi: 10.1016/j.ab.2004.02.012.

Abstract

We report the development and characterization of a polyacrylamide-based protein immobilization strategy for surface-bound protein assays, including concentration detection, binding affinity, and enzyme kinetics. Glutathione S-transferase (GST) fusion proteins have been labeled with an acrylic moiety and attached to acrylic-functionalized glass surfaces through copolymerization with acrylic monomer. The specific attachment of GST-green fluorescent protein (GFP) fusion protein was more than sevenfold greater than the nonspecific attachment of nonacrylic-labeled GST-GFP; 0.32 ng/mm(2) of surface-attached GST-GFP was detectable by direct measurement of GFP fluorescence and this lower detection limit was reduced to 0.080 ng/mm(2) using indirect antibody-based detection. The polyacrylamide-based surface attachment strategy was also used to measure the kinetics of substrate phosphorylation by the kinase c-Src. Michaelis-Menten kinetic constants for the reaction occurring in solution were K(m) = 2.7 +/- 1.0 microM and V(max) = 8.1 +/- 3.1 (arbitrary units). Kinetic values for the reaction utilizing surface-immobilized substrate were K(m) = 0.36 +/- 0.033 microM and V(max) = 9.7 +/- 0.63 and were found to be independent of the acrylamide concentration within the copolymer. Such a surface attachment strategy should be applicable to the proteomics field and addresses denaturation and dehydration problems associated with protein microarray development.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Acrylic Resins*
  • Enzymes, Immobilized
  • Glass
  • Glutathione Transferase*
  • Hydrogels*
  • Proteins / analysis*
  • Proteins / metabolism
  • Recombinant Fusion Proteins

Substances

  • Acrylic Resins
  • Enzymes, Immobilized
  • Hydrogels
  • Proteins
  • Recombinant Fusion Proteins
  • polyacrylamide
  • Glutathione Transferase