We use oxalate oxidase from barley seedlings for the colorimetric determination of oxalate in plasma. The oxalate is converted to hydrogen peroxide, which, in the presence of peroxidase, is detected by a Trinder-like chromogenic system. Optimization of the assay, including deproteinization and elimination of interferences from reducing substrates, is described. Ascorbate additions (200 mumol/L)...

A novel spectrophotometric enzymlc procedure for estimating oxalic acid in urine is described. Oxalate oxidase, prepared from moss species, converts oxalic acid to hydrogen peroxide and carbon dioxide. Hydrogen peroxide is determined enzymatically with horseradish peroxidase, by oxidative coupling of 3-methyl-2-benzothiazolinone hydrazone with N,N-dimethylaniline; the resulting indamine dye is ...

Considering the widespread occurrence of oxalate in nature and its broad impact on a host of organisms, it is surprising that so little is known about the turnover of this important acid. In plants, oxalate oxidase is the most well studied enzyme capable of degrading oxalate, but not all plants possess this activity. Recently, an Acyl Activating Enzyme 3 (AAE3), encoding an oxalyl-CoA synthetas...

The external pH appeared to be the main factor governing oxalic acid production by Aspergillus niger. A glucose-oxidase-negative mutant produced substantial amounts of oxalic acid as long as the pH of the culture was 3 or higher. When pH was decreased below 2, no oxalic acid was formed. The activity of oxaloacetate acetylhydrolase (OAH), the enzyme believed to be responsible for oxalate formati...

Red beet root discs aerated in potassium phosphate for 2 to 3 days and young spinach leaves actively produce oxalate. A series of labeled compounds was supplied to each of these tissues to determine the extent of conversion to oxalate. Similar results were obtained with the 2 tissues except that in the leaf tissue glyoxylate and glycolate were outstandingly good precursors. Carbon from glucose,...

Oxalate decarboxylase (OxDC) catalyzes the conversion of oxalate into formate and carbon dioxide in a remarkable reaction that requires manganese and dioxygen. Previous studies have shown that replacing an active-site loop segment Ser(161)-Glu(162)-Asn(163)-Ser(164) in the N-terminal domain of OxDC with the cognate residues Asp(161)-Ala(162)-Ser-(163)-Asn(164) of an evolutionarily related, Mn-d...

Oxalic acid is widely distributed in plants. Although its concentration is not normally high, certain plants such as Oxalis sp., Begonia sp., rhubarb, and spinach contain large amounts of the acid. Cotyledons of spinach, for example, have been reported to contain up to 26% dry weight of oxalic acid (4). The only enzyme system previously reported to metabolize oxalate in plants is oxalate oxidas...

The measurement of oxalate in urine and plasma continues to be difficult, particularly in the presence of ascorbate. We have modified and validated a colorimetric assay involving the use of oxalate oxidase (EC 1.2.3.4). Modification of an HPLC spectrophotometric detector improved sensitivity (to as much as 1000-fold that of conventional spectrophotometers) and allowed measurement of oxalate con...