Dehydratase

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Federal government websites often end in. The site is secure. Lead poisoning affects many organs in the body. Our meta-analysis studied the effects of the ALAD polymorphism on a blood and bone lead levels and b indicators of target organ toxicity. Sample sizes, means, and standard deviations were extracted for the genotype groups. There was a statistically significant association between ALAD2 carriers and higher BLL in lead-exposed workers weighted mean differences of 1. ALAD2 carriers were potentially protected against adverse hemapoietic effects ZPP and hemoglobin levels , perhaps because of decreased lead bioavailability to heme pathway enzymes.

Dehydratase

Dehydratases are a group of lyase enzymes that form double and triple bonds in a substrate through the removal of water. Dehydratases can act on hydroxyacyl-CoA with or without cofactors , and some have a metal and non-metal cluster act as their active site. A dehydratase deficiency in the body can lead to a less severe condition of hyperphenylalaninemia , which involves an over presence of phenylalanine in the blood. It is caused by a genetic recessive disorder in the autosomal DNA. This enzyme -related article is a stub. You can help Wikipedia by expanding it. Contents move to sidebar hide. Article Talk. Read Edit View history. Tools Tools. Download as PDF Printable version. Group of lyase enzymes. The Free Dictionary. Retrieved Genetics Home Reference.

As his-tag dehydratase PksH possesses the same molecular weight as uncleaved PksI a single band is observed on the gel. Endothelial NOS converts l -arginine into nitric oxide, causing relaxation of vascular smooth muscle Vaziri and Ding ; Vaziri et al. The conserved Arg is located rather close 4, dehydratase, dehydratase.

Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. The members of this family are involved in various biosynthetic and carbohydrate metabolic pathways. The active site is located at the monomer-monomer interface and contains residues from both the N-terminal recognition helix and the C-terminus of the dimeric counterpart. The active site also contains a conserved Ser, which probably acts as a base in catalysis.

Federal government websites often end in. The site is secure. Preview improvements coming to the PMC website in October Learn More or Try it out now. Biosynthesis of 6-deoxy sugars, including l -fucose, involves a mechanistically complex, enzymatic 4,6-dehydration of hexose nucleotide precursors as the first committed step. Here, we determined pre- and postcatalytic complex structures of the human GDP-mannose 4,6-dehydratase at atomic resolution. We show that concerted acid—base catalysis from only two active-site groups, Tyr and Glu , promotes a syn 1,4-elimination from an enol not an enolate intermediate. Their biosynthetic pathways have in common that 4,6-dehydration of a hexose nucleotide precursor constitutes the first committed step. We show, based on high-resolution pre- and postcatalytic complex structures of the enzyme, that human GDP-mannose 4,6-dehydratase hGMD represents a perfect realization of that principle in its most parsimonious form. We suggest that other sugar 1,4-dehydratases like dTDP-glucose 4,6-dehydratase 13 , 24 employ the same principle, but in an expanded version.

Dehydratase

Related to dehydratase: threonine dehydratase. All rights reserved. A subclass of lyases hydro-lyases that remove H and OH as H 2 O from a substrate, leaving a double bond, or add a group to a double bond by the elimination of water from two substances to form a third; synthase is sometimes used when the synthetic aspect of the reaction is emphasized.

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The differences between the catalytic efficiency thus probably originate from the recognition helix and C-terminus, which highlights the important role of the dimerization. Cells were harvested by centrifugation and processed as outlined for PksH and PksI proteins. Address correspondence to F. When we found a discrepancy in the reported studies, the authors were contacted and the corrected data were used. The sequences of all constructs were verified by DNA sequencing prior to protein expression studies. Am J Hum Genet. Multicompartment kinetic models for lead: Part I. Thus, a total of 14 studies were included in our analysis of blood lead level and ALAD polymorphism. Ethics declarations Competing Interests The authors declare that they have no competing interests. Figure 5. Chapter 1 introduction to polyketide biosynthesis. PksH was amplified from B. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate. Electronic supplementary material. Haines, A.

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Schwartz et al. Nair and Alice Robson. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate. Several epidemiologic studies have attempted to correlate the ALAD allelic variations with a differential susceptibility to lead poisoning. The specificity of these protein—protein interactions affords a degree of control over branch placement, opening up intriguing possibilities for the relocation of synthase embedded ACPs upon which branches are assembled to alternative sites within HCS-cassette containing PKSs. Evidence for association of a common variant of the endothelialnitric oxide synthase gene Glu—Asp polymorphism to the presence, extent, and severity of coronary artery disease. Received : 18 October As a library, NLM provides access to scientific literature. Helfrich, E. Calderone, C. Sample sizes, means, and standard deviations were extracted for the genotype groups.