Matrix-Bound Phosphoglucose Isomerase

Formation and Properties of Monomers and Hybrids

Authors

  • Peter BRUCH,

    1. Chirurgische Klinik und Poliklinik der Julius-Maximilians-Universität Würzburg, Josef-Schneider-Straße 2, D-8700 Würzburg, Federal Republic of Germany
    Search for more papers by this author
  • Klaus D. SCHNACKERZ,

    Corresponding author
    1. Physiologisch-Chemisches Institut der Julius-Maximilians-Universität Würzburg, Koellikerstraße 2, D-8700 Wurzburg, Federal Republic of Germany
    Search for more papers by this author
  • Robert W. GRACY

    1. Department of Chemistry, North Texas State University, Denton, Texas. U.S.A. 76203
    Search for more papers by this author

To whom correspondence should be addressed.

Abstract

Dimeric phosphoglucose isomerase from rabbit muscle was immobilized by reaction with cyanogen-bromide-activated Sepharose 4B. The catalytic parameters and stability properties of the free and matrix-bound isomerases were essentially identical. Total monomerisation of the matrix-bound enzyme was achieved with 8 M urea as determined by a study in which one subunit was labelled with iodo[14C]acetate and the other with the 3H-labelled reagent. Although matrixbound monomers were devoid of isomerase activity, they were still capable of binding the substrate. Matrix-bound monomers exhibited the ability to redimerize with soluble isomerase subunits from either rabbit or human yielding catalytically active dimers. Yeast isomerase monomers, in contrast, did not yield active hybrids with the rabbit monomers. Furthermore, soluble subunits, which had been inactivated with pyridoxal 5′-phosphate were also capable of hybridizing with and inducing catalytic activity in the matrix-bound monomers. These studies indicate the prerequisite of dimer formation for catalytic activity but the independent action of the catalytic centers of the dimer.

Ancillary