Effect of Fluorosis on Liver Cells of VC Deficient and Wild Type Mice

For decades, mouse and other rodents have been used for the study of oxidative or related studies such as the effect of fluoride. It is known that rodents normally synthesize their own vitamin C (VC) due to the presence of a key enzyme in ascorbic acid synthesis, l-gulono-lactone-γ-oxidase (Gulo), while humans do not have the capacity of VC synthesis due to the deletion of most parts of the GULO gene. The spontaneous fracture (sfx) mouse recently emerged as a model for study of VC deficiency. We investigated the effect of fluoride on liver cells from wild type Balb/c andsfxmice. We found that activities of SOD, GPx, and CAT were reduced in both wild type andsfxmice; however, the amount of reduction in thesfxcells is more than that in Balb/c cells. In addition, while both cells increased MDA, the increase in thesfxcells is greater than that in Balb/c cells. Gene networks ofSod,Gpx, andCatin the liver of humans and mice are also different. Our study suggests that reaction to fluoride in vitamin C deficient mice might be different from that of wild type mice.

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Endogenous ascorbic acid synthesis and recommended dietary allowances for vitamin C

American Journal of Clinical Nutrition ◽

10.1093/ajcn/34.7.1448 ◽

1981 ◽

Vol 34 (7) ◽

pp. 1448-1449 ◽

Cited By ~ 8

Author(s):

E Ginter

Keyword(s):

Ascorbic Acid ◽

Vitamin C ◽

Acid Synthesis ◽

Recommended Dietary Allowances ◽

Ascorbic Acid Synthesis

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Iterative Saturation Mutagenesis of −6 Subsite Residues in Cyclodextrin Glycosyltransferase from Paenibacillus macerans To Improve Maltodextrin Specificity for 2-O-d-Glucopyranosyl-l-Ascorbic Acid Synthesis

Applied and Environmental Microbiology ◽

10.1128/aem.02918-13 ◽

2013 ◽

Vol 79 (24) ◽

pp. 7562-7568 ◽

Cited By ~ 15

Author(s):

Ruizhi Han ◽

Long Liu ◽

Hyun-dong Shin ◽

Rachel R. Chen ◽

Jianghua Li ◽

...

Keyword(s):

Ascorbic Acid ◽

Substrate Binding ◽

Acid Synthesis ◽

Saturation Mutagenesis ◽

Wild Type ◽

Cyclodextrin Glycosyltransferase ◽

Content Type ◽

Paenibacillus Macerans ◽

Ascorbic Acid Synthesis ◽

Iterative Saturation Mutagenesis

ABSTRACT2-O-d-Glucopyranosyl-l-ascorbic acid (AA-2G), a stablel-ascorbic acid derivative, is usually synthesized by cyclodextrin glycosyltransferase (CGTase), which contains nine substrate-binding subsites (from +2 to −7). In this study, iterative saturation mutagenesis (ISM) was performed on the −6 subsite residues (Y167, G179, G180, and N193) in the CGTase fromPaenibacillus maceransto improve its specificity for maltodextrin, which is a cheap and easily soluble glycosyl donor for AA-2G synthesis. Site saturation mutagenesis of four sites—Y167, G179, G180, and N193—was first performed and revealed that four mutants—Y167S, G179R, N193R, and G180R—produced AA-2G yields higher than those of other mutant and wild-type CGTases. ISM was then conducted with the best positive mutant as a template. Under optimal conditions, mutant Y167S/G179K/N193R/G180R produced the highest AA-2G titer of 2.12 g/liter, which was 84% higher than that (1.15 g/liter) produced by the wild-type CGTase. Kinetics analysis of AA-2G synthesis using mutant CGTases confirmed the enhanced maltodextrin specificity and showed that compared to the wild-type CGTase, the mutants had no cyclization activity but high hydrolysis and disproportionation activities. A possible mechanism for the enhanced substrate specificity was also analyzed through structure modeling of the mutant and wild-type CGTases. These results indicated that the −6 subsite played crucial roles in the substrate binding and catalytic reactions of CGTase and that the obtained CGTase mutants, especially Y167S/G179K/N193R/G180R, are promising starting points for further development through protein engineering.

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VITAMIN C METABOLISM IN RATS FED A LOW-PROTEIN DIET AND EXPOSED TO COLD

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y67-037 ◽

1967 ◽

Vol 45 (2) ◽

pp. 335-342 ◽

Cited By ~ 1

Author(s):

John R. Beaton

Keyword(s):

Ascorbic Acid ◽

Body Weight ◽

Vitamin C ◽

Cold Exposure ◽

Acid Synthesis ◽

Protein Diet ◽

Male Rats ◽

Low Protein Diet ◽

Low Protein ◽

Ascorbic Acid Synthesis

Male rats of the Wistar strain were fed a low-protein (5% casein) or a control (20% casein) diet at environmental temperatures of 24 and 5 °C. Measurements were made of daily food intake, body weight, and urinary excretion of vitamin C, and of ascorbic acid synthesis and destruction by liver homogenates in vitro. From the results of several experiments it was observed that (a) rats fed the low-protein diet excreted decreased amounts of vitamin C which were increased by exposure to cold; (b) ascorbic acid synthesis was decreased in rats fed the low-protein diet; (c) ascorbic acid synthesis was increased by cold exposure in rats fed the low-protein diet ad libitum but not when pair-fed; (d) destruction of ascorbic acid was not affected markedly by either dietary protein level or by cold exposure; (e) subcutaneous injection of ascorbic acid (5 mg/100 g body weight) significantly increased body weight gain in rats fed the low-protein diet at 24 and 5 °C and in rats fed the control diet at 5 °C. These observations indicate an inadequate synthesis of ascorbic acid in rats fed a low-protein diet.

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