Accession Number:

ADA019088

Title:

Role of Hemin in the Acid Aggregation of Horseradish Peroxidase.

Descriptive Note:

Technical rept. Nov 70-Jun 74,

Corporate Author:

EDGEWOOD ARSENAL ABERDEEN PROVING GROUND MD

Report Date:

1975-11-01

Pagination or Media Count:

30.0

Abstract:

Expulsion of hemin from horseradish peroxidase at pH 2.1 is accompained by aggregation of the protein. The process is completely reversible after short periods in acid and is partially reversible after long periods 48 hours. On gel filtration of peroxidase immediately after acidification, hemin and the protein elute together. Apoperoxidase pH 2.1 elutes much later about the same elution volume as neutral enzyme than peroxidase pH 2.1 indicating a hemin requirement for the aggregation. Analytical sedimentation velocity and sucrose density gradient sedimentation of peroxidase immediately after acidification reveal a 7.8S component with both 400-nm and 280-nm absorbance and a 4S component with 280-nm abosrbance. Sedimentation velocity studies of hemin in the presence of bovine serum albumin or rabbit immunoglobulin G reveal hemin aggregation without hemin precipitation or protein aggregation. A molecular weight of about 80,000 for the peroxidase-hemin aggregate has been determined by membrane osmometry.

Subject Categories:

  • Biochemistry
  • Organic Chemistry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE