What Differs on the Enzymatic Acetylation Mechanisms for Arylamines and Arylhydrazines Substrates? A Theoretical Study

The acetylation mechanisms of several selected typical substrates from experiments, including arylamines and arylhydrazines, are investigated with the density functional theory in this paper. The results indicate that all the transition states are characterized by a four-membered ring structure, and hydralazine (HDZ) is the most potent substrate. The bioactivity for all the compounds is increased in a sequence ofPABA≈4-AS<4-MA<5-AS≈INH<HDZ. The conjunction effect and the delocalization of the lone pairs of N atom play a key role in the reaction. All the results are consistent with the experimental data.

Multiplex Detection and Genotyping of Point Mutations Involved in Charcot-Marie-Tooth Disease Using a Hairpin Microarray-Based Assay

We previously developed a highly specific method for detecting SNPs with a microarray-based system using stem-loop probes. In this paper we demonstrate that coupling a multiplexing procedure with our microarray method is possible for the simultaneous detection and genotyping of four point mutations, in three different genes, involved in Charcot-Marie-Tooth disease. DNA from healthy individuals and patients was amplified, labeled with Cy3 by multiplex PCR; and hybridized to microarrays. Spot signal intensities were 18 to 74 times greater for perfect matches than for mismatched target sequences differing by a single nucleotide (discrimination ratio) for “homozygous” DNA from healthy individuals. “Heterozygous” mutant DNA samples gave signal intensity ratios close to 1 at the positions of the mutations as expected. Genotyping by this method was therefore reliable. This system now combines the principle of highly specific genotyping based on stem-loop structure probes with the advantages of multiplex analysis.

Inhibition ofCandida albicansby Fluvastatin Is Dependent on pH

The cholesterol-lowering drug fluvastatin (FS) has an inhibitory effect on the growth of the pathogenic yeastCandida albicansthat is dependent on the pH of the medium. At the low pH value of the vagina, FS is growth inhibitory at low and at high concentrations, while at intermediate concentrations (1–10 mM), it has no inhibitory effect. Examination of the effect of the common antifungal drug fluconazole in combination with FS demonstrates drug interactions in the low concentration range. Determination of intracellular stress and the activity of the FS target enzyme HMG-CoA reductase confirm our hypothesis that in the intermediate dose range adjustments to the sterol biosynthesis pathway can compensate for the action of FS. We conclude that the pH dependent uptake of FS across yeast membranes might make FS combination therapy an attractive possibility for treatment of vaginalC. albicansinfections.

Two Distantly Spaced Basic Patches in the Flexible Domain of Huntingtin-Interacting Protein 1 (HIP1) Are Essential for the Binding of Clathrin Light Chain

The interaction between HIP family proteins (HIP1 and HIP12/1R) and clathrin is fundamental to endocytosis. We used circular dichroism (CD) to study the stability of an HIP1 subfragment (aa468-530) that is splayed open. CD thermal melts show HIP1 468-530 is only stable at low temperatures, but this HIP1 fragment contains a structural unit that does not melt out even at 83C∘. We then created HIP1 mutants to probe our hypothesis that a short hydrophobic path in the opened region is the binding site for clathrin light chain. We found that the binding of hub/LCb was sensitive to mutating two distantly separated basic residues (K474 and K494). The basic patches marked by K474 and K494 are conserved in HIP12/1R. The lack of conservation insla2p (S. cerevisiae), HIP1 fromD. melanogaster, and HIP1 homolog ZK370.3 fromC. elegansimplies the binding of HIP1 and HIP1 homologs to clathrin light chain may be different in these organisms.

Dephosphorylation of Centrins by Protein Phosphatase 2C and

In the present study, we identified protein phosphatases dephosphorylating centrins previously phosphorylated by protein kinase CK2. The following phosphatases known to be present in the retina were tested: PP1, PP2A, PP2B, PP2C, PP5, and alkaline phosphatase. PP2C and were capable of dephosphorylating P--centrin1 most efficiently. PP2C was inactive and the other retinal phosphatases also had much less or no effect. Similar results were observed for centrins 2 and 4. Centrin3 was not a substrate for CK2. The results suggest PP2C and to play a significant role in regulating the phosphorylation status of centrins in vivo.

Metabolism of a Glycosaminoglycan during Metamorphosis in the Japanese Conger eel,Conger myriaster

Hyaluronan (HA) is a linear polysaccharide of high molecular weight that exists as a component of the extracellular matrix. The larvae (leptocephali) of the Japanese conger eel (Anguilliformes:Conger myriaster) have high levels of hyaluronan (HA) which is thought to help control body water content. We isolated glycosaminoglycans (GAGs) from Japanese conger eel leptocephali and measured the changes in tissue HA content during metamorphosis. HA content decreased during metamorphosis. In contrast, neutral sugar content increased during metamorphosis. We hypothesize that the leptocephali utilize a metabolic pathway that converts HA to glucose during metamorphosis. Glucose may then be metabolized to glycogen and stored in the juvenile life-history stage.

Liver X Receptor Agonists Inhibit the Phospholipid Regulatory Gene CTP: Phosphoethanolamine Cytidylyltransferase-Pcyt2

Metabolic pulse-chase experiments demonstrated that 25-hydroxycholesterol (25-OH), the endogenous activator of the liver X receptor (LXR), significantly reduced the biosynthesis of phosphatidylethanolamine via CDP-ethanolamine (Kennedy) pathway at the step catalyzed by CTP: phosphoethanolamine cytidylyltransferase (Pcyt2). In the mouse embryonic fibroblasts C3H10T1/2, the LXR synthetic agonist TO901317 lowered Pcyt2 promoter-luciferase activity in a concentration-dependent manner. Furthermore, 25-OH and TO901317 reduced mouse Pcyt2 mRNA and protein levels by 35–60%. The inhibitory effects of oxysterols and TO901317 on the Pcyt2 promoter function, mRNA and protein expression were conserved in the human breast cancer cells MCF-7. These studies identify the Pcyt2 gene as a novel target whereby LXR agonists may indirectly modulate inflammatory responses and atherosclerosis.

Identification of a New Splice Variant of the Human ABCC6 Transporter

ABCC6 is a member of the adenosine triphosphate-binding cassette (ABC) gene subfamily C that encodes a protein (MRP6) involved in active transport of intracellular compounds to the extracellular environment. Mutations in ABCC6 cause pseudoxanthoma elasticum (PXE), an autosomal recessive disorder of the connective tissue characterized by progressive calcification of elastic structures in the skin, the eyes, and the cardiovascular system. MRP6 is codified by 31 exons and contains 1503 amino acids. In addition to a full-length transcript of ABCC6, we have identified an alternatively spliced variant of ABCC6 from a cDNA of human liver that lacks exons 19 and 24. The novel isoform was named ABCC6 1924. PCR analysis from cDNA of cell cultures of primary human hepatocites and embryonic kidney confirms the presence of the ABCC61924 isoform. Western blot analysis of the embryonic kidney cells shows a band corresponding to the molecular weight of the truncated protein.

An Antithrombin-Heparin Complex Increases the Anticoagulant Activity of Fibrin Clots

Clotting blood contains fibrin-bound thrombin, which is a major source of procoagulant activity leading to clot extension and further activation of coagulation. When bound to fibrin, thrombin is protected from inhibition by antithrombin (AT) + heparin but is neutralized when AT and heparin are covalently linked (ATH). Here, we report the surprising observation that, rather than yielding an inert complex, thrombin-ATH formation converts clots into anticoagulant surfaces that effectively catalyze inhibition of thrombin in the surrounding environment.