| 1. |
- Lilja, H., et al.
(författare)
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Evaluation of serum γ-glutamyltransferase by electrofocusing, and variations in isoform patterns
- 1983
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Ingår i: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 29:6, s. 1034-1037
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Tidskriftsartikel (refereegranskat)abstract
- Serum γ-glutamyltransferase (EC 2.3.2.2) showed microheterogeneity on electrofocusing, owing to variations in sialic acid content. We investigated the isoform patterns of papain-treated serum samples on agarose gels containing nonionic detergent and ampholytes in the low pH range. Serum from cases of cholestasis show seven bands with γ-glutamyltransferase activity. These same bands were also found in liver tissue similarly treated, and they had pl values ranging from 3.8 to 4.2. Papain-treated sera that also had been neuraminidase digested showed only a single band, still enzymatically active and with a pI of 5.9. Increased γ-glutamyltransferase in serum as a result of alcoholic abuse was combined with a abnormally high degree of sialylation of the enzyme, giving more anodal isoforms. The decline in the concentration of this enzyme during several weeks of abstinence was accompanied by a gradual decrease in γ-glutamyltransferase sialylation and the appearance of more cathodal fractions.
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| 2. |
- von Schenck, H, et al.
(författare)
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Interference of immunoglobulins in two glucagon radioimmunoassays
- 1982
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Ingår i: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 28:5, s. 7-1103
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Tidskriftsartikel (refereegranskat)abstract
- Radioimmunoassays of glucagon in plasma may be complicated by interaction with other substances of high molecular mass. Precipitates of such substances with ammonium sulfate showed, after isoelectric focusing, two fractions having glucagon immunoreactivity. One fraction (pl approximately 10) evidently is associated with the Fc portion (but not the Fab portion) of purified polyclonal immunoglobulin G (IgG). Equal amounts of purified monoclonal IgG of various subclasses, especially IgG 1, gave different "glucagon" readings, suggesting that some IgG may interfere more strongly than others. The other fraction (pI 5-6) appeared less consistently, and on gel chromatography appeared to be slightly larger than IgG. Together these fractions add about 50-100 ng/L to the immunoreactive glucagon values in plasma. Therefore methods in which glucagon is extracted before assay should be used for determining the concentration of glucagon present physiologically.
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