THE ROLE OF CARBOHYDRATE IN THE STRUCTURE AND FUNCTION OF NEPHRITIC FACTOR

  • 1 January 1981
    • journal article
    • research article
    • Vol. 46  (1) , 120-129
Abstract
Six nephritic factors (NeF) were purified from the IgG fraction of sera of patients with partial lipodystrophy and/or membranoproliferative glomerulonephritis by elution from EAC43bBb [erythrocyte-antibody-activated complement component 4 plus complement component 3 convertase complex]. All had at least 1 abnormal H chain component when examined by PAGE-SDS [polyacrylamide gel electrophoresis-sodium dodecyl sulfate] and 2 additionally had a large L chain. Four different H chains were found. Their apparent MW and the frequency with which they occurred were: 65,000 (1 NeF), 61,500 (4 NeF), 57,000 (2 NeF) and 55,000 (1 NeF) compared with 53,500 daltons for normal H chain. The MW of the large L chains was 26,500 daltons (cf 23,500 for normal L chain). Both the NeF activity and the large components were located in the F(ab'')2 fragment of the molecule and after reduction the large component was found in the Fd fragment of the H chain. Neuraminidase treatment of purified NeF caused a 1-2% decrease in apparent MW of the large H chain on PAGE-SDS. Mild periodate oxidation, sufficient to cause primarily loss of carbohydrate, caused a marked loss of activity. Reduction and alkylation of NeF under neutral conditions caused only a small loss of activity but after acid dissociation the H and L chains were completely inactive.