A new, simple and sensitive method is described for assay of serum γ-glutamyltransferase activity based on the hydrolysis of the substrate Z,-7-glutamyl-3-carboxy-4-nitranilide which offers the advantage of producing directly its own chromogen.The substrate is highly soluble and the method can therefore easily be adapted to any equipment for the automated assay of γ-glutamyltransferase.The activities at measured optimum substrate concentration are slightly higher than with the Szasz ((1969), Clin. Chem. 15,124-136) method in which i-glutamyl-p-nitroanilide is used as substrate. Eine neue Methode zur Bestimmung der y-Glutamyltfansferase im SerumZusammenfassung: Es wird eine einfache und empfindliche neue Methode f r die Bestimmung der γ-Glutamyltransferase-Aktivit t im Serum beschrieben. Sie beruht auf der Hydrolyse des Substrats Z,-7-Glutamyl-3-carboxy-4-nitranilid.Die Freisetzung von 3-Carboxy-4-nitroanilin wird kontinuierlich bei 405 nm gemessen.Das Substrat ist sehr gut l slich. Die Methode kann daher vorz glich auf alle automatischen Analysen-Ger te adaptiert werden.Bei Messung im Substrat-Optimum ergibt die neue Methode etwas (l,22fache) h here Werte als die bisher generell verwendete Bestimmung der 7-Gl tamyltransferase nach&flsz ((1969), Clin. Chem. 15,124-136) mit L-Glutamyl-. p-nitranilid als Substrat. Die Korrelatiofiskoeffizient beider Methoden betrug r = 0.999.

No abstract

No abstract

No abstract

In vitro-synthesized carbamylated and acetylated hemoglobins interfered in assays of glycohemoglobin by HPLC and electrophoresis but had no effects on results obtained by affinity chromatography and enzyme immunoassay. Correlations between long-term serum urea concentrations and glycohemoglobin percentages revealed that, in vivo, carbamylated hemoglobin equivalent to 0.063% of total hemoglobin is formed for every 1 mmol/L of serum urea. The use of acetylsalicylate, either chronically in small doses (200-300 mg/day) or for 1 week at 2000 mg/day, did not cause significant interference from acetylhemoglobin, formed in vivo. We conclude that interference from carbamylated hemoglobin explains only a small part of existing discrepancies between results of glycohemoglobin assays in current use. The interfering effect of acetylhemoglobin formed in vivo with acetyl-CoA as substrate is as yet unknown.