Tyrosine hydroxylase activity is reversibly controlled by the actions of several protein kinases. Previous studies showed that, following phosphorylation by protein kinase A, physiological concentrations of ascorbate irreversibly inactivate tyrosine hydroxylase. Several studies were performed to establish the mechanism of inactivation. We found that inactivation occurred under oxygen-free condi...

A double-masked study of the effects of topical ascorbate on alkali burns utilized 37 rabbit eyes subjected to 20 sec, 12 mm, IN sodium hydroxide burns. Preliminary studies established the ocular acceptability, penetrability, and stability of the solutions used. Eighteen eyes in the experimental group were given two drops of10% ascorbate in Adsorbotear vehicle hourly for 14 hr of each day. Nine...

The present investigation addresses the problem of the binding mode of phenolic inhibitors and the substrate ascorbate to the active site of ascorbate oxidase. The results from both types of compounds indicate that the binding site is located in a pocket near the type 1 copper center. This information is of general interest for blue multicopper oxidases. Docking calculations performed on the as...

The promoting effect of sodium L-ascorbate on two-stage urinary bladder carcinogenesis in F344 rats initiated with N-butyl-N-(4-hydroxybutyl)nitrosamine at levels of 0.01 and 0.05% in drinking water was studied. Administration of 5.0% but not of 1.0% sodium L-ascorbate in the diet significantly increased the incidence and number of preneoplastic lesions, papillary or nodular hyperplasia, papill...

BACKGROUND Vitamin C (ascorbate) is likely to be essential for skeletal muscle structure and function via its role as an enzyme cofactor for collagen and carnitine biosynthesis. Vitamin C may also protect these metabolically active cells from oxidative stress. OBJECTIVE We investigated the bioavailability of vitamin C to human skeletal muscle in relation to dietary intake and plasma concentra...

We used constant potential in vivo voltammetry to measure changes in striatal ascorbate in the rat in response to i.p. administration of several non-volatile anaesthetics. Propofol and pentobarbitone, which enhance GABA-mediated neuronal inhibitions, decreased ascorbate current to 27.0 (SEM 7.4) % and 46 (6) % of control, respectively. Chloral hydrate, diazepam alone or with ketamine, and fenta...

The effects of different levels black pepper (5, 10 or 15 g/kg) and the use ascorbate (without with ascorbate) on volatile compounds sucuk were examined in study. samples belonging to each group extracted by solid phase micro-extraction (SPME) analyzed gas chromatography-mass spectrometry (GC-MS). Ascorbate was not effective aldehydes, aromatic hydrocarbons, esters, acids terpenes. While high l...

A new procedure has been described for the isolation and purification of ascorbate oxidase from green zucchini squash (Cucurbita pepo meduttosa). The new purification method achieves a more than ZOO-fold purification with about a 14% recovery of the total activity present in the crude juice. The purified enzyme preparations have been found to be homogeneous by the criteria of ultracentrifugal a...

Previous work from our laboratory demonstrated that pyridoxal isonicotinoyl hydrazone (PIH) has in vitro antioxidant activity against iron plus ascorbate-induced 2-deoxyribose degradation due to its ability to chelate iron; the resulting Fe(III)-PIH(2) complex is supposedly unable to catalyze oxyradical formation. A putative step in the antioxidant action of PIH is the inhibition of Fe(III)-med...