Plant microbody proteins. II. Purification and characterization of the major protein component (SP-63) of peroxisome membranes.

The major component of membranes of microbodies from green leaves of Lens culinaris is a protein of a subunit molecular weight of 63 000. This protein, referred to as SP-63, seems to be unique to microbodies and could not be detected when plastids or mitochondria were analyzed. It is probably a structural protein and is thus not solubilized by cholate, Triton X-100, chloroform/methanol, or 0.2M KCl. Solubilization from purified membranes was achieved with guanidinium chloride or sodium dodecylsulphate. The protein was separated from minor contaminating components by chromatography on Sepharose 4B or Sephadex G-150 employing 0.1% sodium dodecylsulphate or 4M urea as eluent. It was shown to be homogeneous upon sodium dodecylsulphate gel electrophoresis and did not give a positive glycoprotein stain.