Title: [33] Aldohexose dehydrogenase from Gluconobacter cerinus
Abstract: This chapter describes the assay method, purification procedure, and properties of aldohexose dehydrogenase from gluconobacter cerinus. The assay is based on the spectrophotometric determination of NADPH formed with D-mannose as substrate. The assay system (1.01–1.02 ml), in addition to enzyme, contains: 0.8 ml of Tris HC1, 0.1 ml of D-mannose and 0.1 ml NADP+. The reaction is initiated by the addition of NADP+ and the changes in absorbance at 340 nm are determined at 30° with a multiple sample absorbance recording spectrophotometry. All steps of purification procedure are carried out at 0–4°. The addition of iodoacetate, N-ethylmaleimide, p-hydroxymercuribenzoate, and 5,5’-dithiobis-(2-nitrobenzoic acid) (in concentrations ranging from 0.5 mM to 20 mM) to the standard aldohexose dehydrogenase assay mixture does not inhibit the rate of hexose oxidation. The presence of 1 mM ZnSO4 or CuSO4, however, results in the complete inactivation of the enzyme. The aldohexose dehydrogenase from G. cerinus is unusual in its specificity; thus, it does not catalyze the oxidation of aldopentoses and is completely inactive with NAD+. Furthermore, oxidation of D-man nose is a relatively unusual feature of the aldose dehydrogenases hitherto obtained from various sources. However, NADP+-linked oxidation of D-mannose has been observed in extracts derived from two stains of Acetobacter suboxydans, which are indeed closely related to the Gluconobacter group.
Publication Year: 1975
Publication Date: 1975-01-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
Access and Citation
Cited By Count: 10
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