Phytase activity in the human and rat small intestine.

Iqbal, Tariq; Lewis, K O; Cooper, B T

doi:10.1136/gut.35.9.1233

Cited by 190 publications

(107 citation statements)

References 25 publications

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“…Unique structural characteristics of lethal toxin under neutral pH conditions thereby prevent activation of the CPD by InsP 6 binding prior to cell entry. Such prerequisites might not be necessary for C. difficile toxin B, for example, because phytase enzymes that hydrolyze extracellular luminal InsP 6 efficiently are present in the small intestine (38). After endocytosis, however, all CGTs are exposed to endosomal acidification, resulting in partial unfolding and/or activation of domains involved in membrane insertion and delivery of the enzyme portions across the endosomal membrane.…”

Section: Discussionmentioning

confidence: 99%

Inositol Hexakisphosphate-dependent Processing of Clostridium sordellii Lethal Toxin and Clostridium novyi α-Toxin

Guttenberg¹,

Papatheodorou²,

Genisyuerek³

et al. 2011

Journal of Biological Chemistry

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Clostridium sordellii lethal toxin and Clostridium novyi ␣-toxin, which are virulence factors involved in the toxic shock and gas gangrene syndromes, are members of the family of clostridial glucosylating toxins. The toxins inactivate Rho/Ras proteins by glucosylation or attachment of GlcNAc (␣-toxin). Here, we studied the activation of the autoproteolytic processing of the toxins by inositol hexakisphosphate (InsP 6 ) and compared it with the processing of Clostridium difficile toxin B. In the presence of low concentrations of InsP 6 (<1 M), toxin fragments consisting of the N-terminal glucosyltransferase (or GlcNActransferase) domains and the cysteine protease domains (CPDs) of C. sordellii lethal toxin, C. novyi ␣-toxin, and C. difficile toxin B were autocatalytically processed. The cleavage sites of lethal toxin (Leu-543) and ␣-toxin (Leu-548) and the catalytic cysteine residues (Cys-698 of lethal toxin and Cys-707 of ␣-toxin) were identified. Affinity of the CPDs for binding InsP 6 was determined by isothermal titration calorimetry. In contrast to fulllength toxin B and ␣-toxin, autocatalytic cleavage and InsP 6 binding of full-length lethal toxin depended on low pH (pH 5) conditions. The data indicate that C. sordellii lethal toxin and C. novyi ␣-toxin are InsP 6 -dependently processed. However, full-length lethal toxin, but not its short toxin fragments consisting of the glucosyltransferase domain and the CPD, requires a pH-sensitive conformational change to allow binding of InsP 6 and subsequent processing of the toxin.

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Section: Discussionmentioning

confidence: 99%

Inositol Hexakisphosphate-dependent Processing of Clostridium sordellii Lethal Toxin and Clostridium novyi α-Toxin

Guttenberg¹,

Papatheodorou²,

Genisyuerek³

et al. 2011

Journal of Biological Chemistry

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“…Plant-based diets in developing countries are usually high in phytate, which inhibits mineral absorption [18]. The inhibitory effect of phytate on calcium, iron, and zinc absorption has been established by in vivo as well as community-based studies [19][20][21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Dietary phytate intake inhibits the bioavailability of iron and calcium in the diets of pregnant women in rural Bangladesh: a cross-sectional study

et al. 2016

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Background: Phytate, a potent inhibitor of calcium, iron, and zinc absorption, may hamper the bioavailability of these micronutrients at the time of pregnancy. This study assessed dietary phytate intake and its inhibitory effect on the bioavailability of calcium, iron, and zinc from the diets of pregnant women in rural Bangladesh. The study also explored significant determinants that predicted the absorption of these minerals from the diet. Methods: A multiple pass recall (MPR) approach was used for this study, with in-depth probing interview covering 24-h dietary recall conducted among 717 pregnant women who were in either their second or third trimester. Results: The mean daily phytate, calcium, iron and zinc intake of the pregnant women were found to be 695.1, 192.2, 5.1, and 5.7 mg respectively. The mean molar ratios of phytate to calcium, iron, zinc and (phytate x calcium)/zinc were 0.27, 12.8, 11.2, and 54.8 respectively. All the molar ratios were found to be significantly higher in a group with the highest phytate intake compared to other intake groups. Phytate inhibited iron absorption from the diet of all the pregnant women sampled, and inhibited calcium absorption among 52 % of the women while inhibition of zinc absorption was not found in a notable number (12 %) of the pregnant women. When using multivariate models, phytate intake, inadequate micronutrient intake, gestational age, and energy intake significantly predicted the variance in phytate to mineral molar ratios. The predicting models calculated about 92 %, 88 %, and 89 % variance in phytate to calcium, iron, and zinc molar ratios respectively. Phytate to calcium, iron, and zinc molar ratios would be expected to be respectively 0.05, 2.48, and 1.96 points higher for every 100 mg increment in daily phytate intake. Conclusions: Phytate intake was found to inhibit the bioavailability of iron and calcium from the diets of pregnant women. Moreover, phytate was one of the strongest inhibitory predictors of calcium, iron and zinc bioavailability.

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“…These complexes cannot be digested or absorbed in the gastrointestinal tract of monogastric animals owing to the absence of the intestinal phytase enzyme [34]. Deficiencies of phosphorus and nutritionally important minerals in monogastric animals can be a result of cations bound in the phytic acid salt and of low bioavailability of phosphorus [35,36] The plant oxalis, common ly known as wood sorrel, gave rise to o xalic acid, a strong, organic acid which has been found to be widely distributed in plants [37].…”

Section: Antinutritional Factorsmentioning

confidence: 99%

The Use of Cassava, Sweet Potato and Cocoyam, and Their By-Products by Non – Ruminants

Apata¹,

Babalola²

2012

FOOD

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As the search for alternative sources of energy for non ruminants continues, this review was undertaken to examine the potential value of cassava (Manihot utilissima Pohl.), sweet potato (Ipomea batatas Poir.), cocoyam (Xanthosoma sagittifolium Schott.) and their by-products as dietary supplements for non ruminants. Studies on these roots and tubers showed that, on a dry-weight basis, contained 2.0 -7.9% crude protein, 0.3 -3.1% crude fib re and 72.4 -77.9% starch. The practical use of these roots and tubers in non ruminant feeds is generally low. Th is level of utilizat ion is attributed to the low protein and dry matter and the potentially to xic cyanogenic glycosides in fresh cassava and irritating substance in cocoyam. Processing techniques such as fermentation, soaking, boiling, ensiling and sun-drying are adopted to remove the deleterious substances, and effects on animals. The co mparable performance of pigs and poultry fed vary ing levels of roots and tubers and their by-products with those maintained on maize showed that they can be used as substitutes in non-ru minants diets at certain levels without detrimental effects. To achieve increase in the use of these root crops and their by-products for maize replacement in intensive non-ruminant production systems, adequate protein supplementation and proper processing are essential.

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Phytase activity in the human and rat small intestine.

Cited by 190 publications

References 25 publications

Inositol Hexakisphosphate-dependent Processing of Clostridium sordellii Lethal Toxin and Clostridium novyi α-Toxin

Inositol Hexakisphosphate-dependent Processing of Clostridium sordellii Lethal Toxin and Clostridium novyi α-Toxin

Dietary phytate intake inhibits the bioavailability of iron and calcium in the diets of pregnant women in rural Bangladesh: a cross-sectional study

The Use of Cassava, Sweet Potato and Cocoyam, and Their By-Products by Non – Ruminants

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