Activation energy and lectin affinity chromatography of gamma-glutamyltransferase as a marker for enzyme heterogeneity.
Lectin affinity chromatography of gamma-glutamyl transferase (GGT,EC 2.3.2.2) is able to detect differences in the carbohydrate moiety of the enzyme. Binding of tissue GGT towards lectins is significantly different from serum GGT, showing increased galactosylation in tissue forms. Kidney GGT is less glycosylated than GGT from other tissues (liver, pancreas, prostate, vesiculae seminales). Increases in sialic acid content of GGT are associated with an increase in the activation energy of the catalyzed reaction. Differences in galactose, fucose and N-acetylhexosamine content induce much smaller effects on activation energy. In liver diseases, serum GGT is characterized by an altered affinity against lectins recognizing galactose, fucose and N-acetyglucosamine and by increased activation energy. In patients with liver disease, use of fixed temperature conversion factors can lead to erroneous calculations of serum GGT enzyme activity (errors up to 13.3%).
Delanghe
J R
JR
Department of Clinical Chemistry, University Hospital Ghent, FRG.
De Buyzere
M L
ML
De Scheerder
I K
IK
Faust
U
U
Wieme
R J
RJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers; D002846:Chromatography, Affinity; D004796:Clinical Enzyme Tests; D006801:Humans; D007527:Isoenzymes / Q000097:blood*; D037102:Lectins; D008107:Liver Diseases / Q000201:enzymology*; D008875:Middle Aged; D005723:gamma-Glutamyltransferase / Q000097:blood*
D015415:Biomarkers; D007527:Isoenzymes; D037102:Lectins; D005723:gamma-Glutamyltransferase