Inhibition of α-, β-, γ-, and δ-carbonic anhydrases from bacteria and diatoms with N′-aryl-N-hydroxy-ureas

The inhibition of α-, β-, γ-, and δ-class carbonic anhydrases (CAs, EC 4.2.1.1) from bacteria (Vibrio cholerae and Porphyromonas gingivalis) and diatoms (Thalassiosira weissflogii) with a panel of N’-aryl-N-hydroxy-ureas is reported. The α-/β-CAs from V. cholerae (VchCAα and VchCAβ) were effectively inhibited by some of these derivatives, with K_Is in the range of 97.5?nM – 7.26?µM and 52.5?nM – 1.81?µM, respectively, whereas the γ-class enzyme VchCAγ was less sensitive to inhibition (K_Is of 4.75 – 8.87?µM). The β-CA from the pathogenic bacterium Porphyromonas gingivalis (PgiCAβ) was not inhibited by these compounds (K_Is?>?10?µM) whereas the corresponding γ-class enzyme (PgiCAγ) was effectively inhibited (K_Is of 59.8?nM – 6.42?µM). The δ-CA from the diatom Thalassiosira weissflogii (TweCAδ) showed effective inhibition with these derivatives (K_Is of 33.3?nM – 8.74?µM). As most of these N-hydroxyureas are also ineffective as inhibitors of the human (h) widespread isoforms hCA I and II (K_Is?>?10?µM), this class of derivatives may lead to the development of CA inhibitors selective for bacterial/diatom enzymes over their human counterparts and thus to anti-infectives or agents with environmental applications.     

Synthesis of β-1, 3-Glucan and β-1, 3 and β-1, 4-Mixed Glucan from UDP-α-d-Glucose

A particulate enzyme preparation from Phaseolus aureus (mung bean) seedlings catalyzed the synthesis of a water insoluble β-1,3-glucan from UDP-α-d-glucose (UDPG) at high concentrations (0.4~20 mm) and an alkaline insoluble β-1,3 and β-1,4-mixed glucan from UDPG at a low concentration (8.5 µm).

Furthermore, the two kinds of β-glucan synthetases which were investigated with two reaction systems at high and low concentrations of UDPG had different properties in optimal pH, stability of enzyme activity, and metallic ion requirement.     

Partial sequence homologies between cytoskeletal proteins,c-myc,Rous sarcoma virus and adenovirus proteins,transducin, and β- and γ-crystallins

Computer based sequence comparisons indicate partial sequence homology between human c-myc, Rous sarcoma virus, adenovirus 7, and simian sarcoma virus proteins and the cytoskeletal proteins desmin, keratin and vimentin. In addition, sections of the oncogene proteins showed partial but significant homology to and subunits of transducin, -II and -BP crystallins showed partial but significant homology to the cytoskeletal proteins keratin, vimentin, desmin, and -tubulin, and to adenovirus 7 and simian sarcoma virus transforming gene proteins. -BP crystallin showed partial but significant homology to Rous sarcoma virus protein, and to and y subunits of transducin. Both crystallins showed partial sequence homology to the GTP-binding protein elongation factor TU fromEscherichia coli . These sequence homologies suggest a link between the mechanisms of normal lens cell differentiation, involving modifications to the cytoskeleton and subsequent changes to the pattern of protein synthesis, and mechanisms of neoplastic transformation. Furthermore the transducin-like region on -crystallin may be important for its interaction with lens membranes and the maintenance of short-range order for lens transparency.     

Kinetic study of the quenching reaction of singlet oxygen by α-, β-, γ-, δ-tocotrienols,and palm oil and soybean extracts in solution

Measurements of the singlet oxygen (¹O₂) quenching rates (k_Q (S)) and the relative singlet oxygen absorption capacity (SOAC) values were performed for 11 antioxidants (AOs) (eight vitamin E homologues (α-, β-, γ-, and δ-tocopherols and -tocotrienols (-Tocs and -Toc-3s)), two vitamin E metabolites (α- and γ-carboxyethyl-6-hydroxychroman), and trolox) in ethanol/chloroform/D₂O (50:50:1, v/v/v) and ethanol solutions at 35?°C. Similar measurements were performed for five palm oil extracts 1–5 and one soybean extract 6, which included different concentrations of Tocs, Toc-3s, and carotenoids. Furthermore, the concentrations (wt%) of Tocs, Toc-3s, and carotenoids included in extracts 1–6 were determined. From the results, it has been clarified that the ¹O₂-quenching rates (k_Q (S)) (that is, the relative SOAC value) obtained for extracts 1–6 may be explained as the sum of the product {Σ k_Q^AO-i (S) [AO-i]/100} of the rate constant (k_Q^AO-i (S)) and the concentration ([AO-i]/100) of AO-i (Tocs, Toc-3s, and carotenoid) included.     

Rates of entry and oxidation of acetate,glucose, d(?)-β-hydroxybutyrate,palmitate, oleate and stearate,and rates of production and oxidation of propionate and butyrate in fed and starved sheep

1. Rates of entry and oxidation of a range of metabolites have been measured in tracheostomized sheep (diet, 800g. of lucerne chaff and 100g. of maize/day) by combining isotope-dilution techniques with the continuous measurement of total respiratory gas exchange, and ¹⁴CO₂ production during the intravenous or intraruminal infusion of ¹⁴C-labelled substrates. 2. Mean entry rates in fed and starved (24hr.) sheep respectively, expressed as mg./min./kg. body wt.^0·75, were: glucose, 5·0 (range 4·8–5·1, 2 observations) and 3·8 (3·2–4·2, 4); acetate, 10·8 (9·1–13·5, 4) and 5·8 (1); d(−)-β-hydroxybutyrate, 1·4 (1) and 1·5 (0·8–2·4, 4); palmitate, oleate and stearate (starved sheep only) 1·0 (0·6–1·9, 7), 0·9 (0·2–1·6, 10) and 0·9 (0·5–1·1, 11) respectively. 3. Production rates of propionate and butyrate in continuously feeding sheep were 6·4 (4·7–8·3, 4) and 4·3 (3·4–6·1, 4) mg./min./kg.^0·75 respectively, and in starved (24hr.) sheep were 2·5 (2·2–2·9, 2) and 1·0 (0·8–1·2, 2) mg./min./kg.^0·75 respectively. 4. Calculated terminal values for the specific radioactivity of respiratory ¹⁴CO₂ during measurements of entry rates and production rates were used to calculate the contributions of individual substrates to overall oxidative metabolism. Mean values for fed and starved sheep respectively were: glucose, 9·1 (8·6–9·6, 2) and 11·2 (5·9–15·1, 4)%; acetate, 31·6 (26·8–38·1, 4) and 22·1 (1)%; d(−)-β-hydroxybutyrate, 10·4 (1) and 4·8 (1·9–7·7, 4)%; propionate, 23·0 (13·8–29·9, 4) and 7·1 (6·8–7·4, 2)%; butyrate, 16·5 (13·7–20·5, 4) and 5·3 (5·2–5·3, 2)%; palmitate, oleate and stearate (starved sheep only), 4·7 (2·0–7·7, 7), 4·0 (1·2–6·6, 10) and 4·4 (3·8–5·8, 9)% respectively. The sum of these values for individual substrates in fed and starved sheep, excluding that of β-hydroxybutyrate and after correction of the glucose value for the known interrelations of this substrate with propionate, accounted for 76% and 58% respectively of total production of carbon dioxide. 5. Calculations based on the proportion of substrate entry directly oxidized indicated that the substrates studied accounted for 63% (fed sheep) and 43% (starved sheep) of total energy expenditure measured by oxygen uptake. The contribution of β-hydroxybutyrate was excluded, and corrections were made for glucose–propionate interrelations, and for the different rates of oxidation of the methyl and carboxyl fragments of acetate. 6. The present results have been combined with those obtained earlier in this Laboratory to examine the relationships between rates of substrate entry and oxidation, and concentrations of substrate in blood. Rates of entry of acetate, glucose, d(−)-β-hydroxybutyrate, palmitate and oleate (but not stearate) were well correlated with concentration in blood, and substrate contribution to production of carbon dioxide showed a similar correlation to blood concentration, except with glucose. 7. It was concluded that the general technique is of potential value in providing valid quantitative parameters of animal metabolism.     

Bromine oxidation of methyl α- and β-pyranosides of D-galactose,D-glucose,and D-mannose

Methyl α- and β-pyranosides of D-galactose, D-glucose, and D-mannose have been oxidized with bromine in aqueous solution at various pH values. The resulting keto glycosides were converted into their more-stable O-methyloxime derivatives which were characterized by spectroscopy and chromatography. Oxidation at a ring carbon atom where the hydrogen is axial is hindered by bulky substituents in syn (i.e., a 1,3) diaxial relationship. Thus, the aglycon group in the α anomers protects position 3, the axial HO-4 in galactopyranosides protects position 2, and the axial HO-2 in mannopyranosides protects position 4 from oxidation.     

Synthesis and Properties of P1, P2-, P1, P3- and P1, P4-Dinucleoside Di-, Tri- and Tetraphosphate mRNA 5′-Cap Analogues

Abstract

Chemically synthesized dinucleoside P¹, P²-di-, P¹, P³-tri- and P¹, P⁴-tetraphosphates, derivatives of 5′-linked 7-methylguanosine and guanosine were characterized with respect to their structural properties and functional effect on eukaryotic translation inhibition.     

Synthesis and stereochemistry of 7β- and 7α-amino-, acetamido-, hemisuccinamido- and terephthalamido derivatives of testosterone

The reduction of 3-ethylenedioxy-7-oximino-5-androsten-17β-yl acetate and of its 17β-tetrahydropyranyl ether analog with sodium in ethanol, followed by thin-layer chromatography, allowed the isolation of the corresponding 17β-hydroxy- and 17β-tetrahydropyranyioxy-5-en-7β- and 7α-amines which were also characte-rized as 7-acetamides. The acylation of the two epimeric 17β-hydroxy-5-en-7-amines with succinic anhydride followed by selective saponification of the 17β-hemisuccinate group and diazomethane esterification, gave the corresponding 17β-hydroxy-5-en-7β- and 7α-hemisuccinamido methyl esters characterized also as 17β-acetates. On the other hand, the acylation of the two 17β-tetrahydropyranyl-oxy-5-en-7-amines with the acid chloride of terephthalic acid monomethyi ester led to the more rigid 7β- and 7α-terephthalamido methyl ester side-chains. The acidolysis of the 3-ethyleneketal protecting group of the preceding 5-en-7-N-acyl derivatives regenerated the 4-en-3-oxo function while the 17β-tetrahydropyranyl ether group was cleaved simultaneously into the 17β-alcohol. The four desired 7β- and 7α-hemisuccinamido- and terephthalamido carboxylic side-chain derivatives of 17β-hydroxy-4-androsten-3-one (testosterone) were finally obtained by saponification of the corresponding methyl esters.     

TIMP-1, -2, -3, and -4 in idiopathic pulmonary fibrosis. A prevailing nondegradative lung microenvironment?

Fibroblast proliferation and extracellular matrix accumulation characterize idiopathic pulmonary fibrosis (IPF). We evaluated the presence of tissue inhibitor of metalloproteinase (TIMP)-1, -2, -3, and -4; collagenase-1, -2, and -3; gelatinases A and B; and membrane type 1 matrix metalloproteinase (MMP) in 12 IPF and 6 control lungs. TIMP-1 was found in interstitial macrophages and TIMP-2 in fibroblast foci. TIMP-3 revealed an intense staining mainly decorating the elastic lamina in vessels. TIMP-4 was expressed in IPF lungs by epithelial and plasma cells. TIMP-2 colocalized with Ki67 in fibroblasts, whereas TIMP-3 colocalized with p27 in inflammatory and epithelial cells. Collagenase-1 was localized in macrophages and alveolar epithelial cells, collagenase-2 was localized in a few neutrophils, and collagenase-3 was not detected. MMP-9 was found in neutrophils and subepithelial myofibroblasts. Myofibroblast expression of MMP-9 was corroborated in vitro by RT-PCR. MMP-2 was noticed in myofibroblasts, some of them close to areas of basement membrane disruption, and membrane type 1 MMP was noticed in interstitial macrophages. These findings suggest that in IPF there is higher expression of TIMPs compared with collagenases, supporting the hypothesis that a nondegrading fibrillar collagen microenvironment is prevailing.     

Klotho is a substrate for α-, β- and γ-secretase

Klotho is an anti-aging protein with different functions of the full-length membrane protein and the secreted hormone-like form. Using overexpression and knock-down approaches as well as embryonic fibroblasts of knock-out mice we present evidence that Klotho is shedded by the α-secretases ADAM10 and 17 as well as by the β-secretase β-APP cleaving enzyme 1. The remaining membrane-bound fragment is a substrate for regulated intramembrane proteolysis by γ-secretase. Our data suggest that therapeutic approaches targeting these proteases should be carefully analyzed for potential side effects on Klotho-mediated physiological processes.     

Characterization of the mRNAs for α-, β- and γ-actin

The mRNAs for α-, β- and γ-actin have been characterized with respect to molecular weight and poly(A) content. Polyacrylamide gel electrophoresis under denaturing conditions shows that the mRNA for α-actin (muscle-specific actin) is approximately 4.6 × 10⁵ daltons in size, and that the mRNAs for β- and γ-actin (nonmuscle actins) are much larger, approximately 6.6 × 10⁵ daltons in size. We therefore calculate that the noncoding regions of the β- and γ-actin mRNAs contain about 800 nucleotides. This is in marked contrast to the noncoding regions of α-actin mRNA which contain only about 180 nucleotides. During electrophoresis in high-resolution nondenaturing gels, the β-actin mRNA migrates slightly slower than the γ-actin mRNA. This indicates either that β-actin mRNA is about 100 nucleotides longer than γ-actin mRNA, or that these mRNAs differ in secondary structure. Fractionation of actin mRNA on the basis of poly(A) content shows that a substantial portion of the β-actin mRNA, but very little of the α- or γ-actin mRNAs, fails to bind to oligo(dT)-cellulose. Much of this poly(A)-deficient β-actin mRNA, however, does bind to poly(U)-Sepharose, a substrate with higher affinity for short poly(A) sequences. This indicates that many of these β-actin mRNA molecules are polyadenylated, but that they have unusually short poly(A) tails. The finding that β- and γ-actins are translated from mRNAs of different electrophoretic mobility and different poly(A) content strongly suggests that these two closely related proteins are products of different genes.     

Modulation of the conformation,fibrillation, and fibril morphologies of human brain α-, β-, and γ-synuclein proteins by the disaccharide chemical chaperone trehalose

Human α-, β-, and γ-synuclein (syn) are natively unfolded proteins present in the brain. Deposition of aggregated α-syn in Lewy bodies is associated with Parkinson's disease (PD) and γ-syn is known to be involved in both neurodegeneration and breast cancer. At physiological pH, while α-syn has the highest propensity for fibrillation followed by γ-syn, β-syn does not form any fibrils. Fibril formation in these proteins could be modulated by protein structure stabilizing osmolytes such as trehalose which has an exceptional stabilizing effect for globular proteins. We present a comprehensive study of the effect of trehalose on the conformation, aggregation, and fibril morphology of α-, β-, and γ-syn proteins. Rather than stabilizing the intrinsically disordered state of the synucleins, trehalose accelerates the rate of fibril formation by forming aggregation-competent partially folded intermediate structures. Fibril morphologies are also strongly dependent on the concentration of trehalose with ≤ 0.4M favoring the formation of mature fibrils in α-, and γ-syn with no effect on the fibrillation of β-syn. At ≥ 0.8M, trehalose promotes the formation of smaller aggregates that are more cytotoxic. Live cell imaging of preformed aggregates of a labeled A90C α-syn shows their rapid internalization into neural cells which could be useful in reducing the load of aggregated species of α-syn. The findings throw light on the differential effect of trehalose on the conformation and aggregation of disordered synuclein proteins with respect to globular proteins and could help in understanding the effect of osmolytes on intrinsically disordered proteins under cellular stress conditions.     

Thermotoga maritima AglA, an extremely thermostable NAD+-, Mn2+-, and thiol-dependent α-glucosidase

The gene for the α-glucosidase AglA of the hyperthermophilic bacterium Thermotoga maritima MSB8, which was identified by phenotypic screening of a T. maritima gene library, is located within a cluster of genes involved in the hydrolysis of starch and maltodextrins and the uptake of maltooligosaccharides. According to its primary structure as deduced from the nucleotide sequence of the gene, AglA belongs to family 4 of glycosyl hy-drolases. The enzyme was recombinantly expressed in Escherichia coli, purified, and characterized. The T. maritimaα-glucosidase has the unusual property of requiring NAD⁺ and Mn²⁺ for activity. Co²⁺ and Ni²⁺ also activated AglA, albeit less efficiently than Mn²⁺. T. maritima AglA represents the first example of a maltodextrin-degrading α-glucosidase with NAD⁺ and Mn²⁺ requirement. In addition, AglA activity depended on reducing conditions. This third requirement was met by the addition of dithiothreitol (DTT) or β-mercaptoethanol to the assay. Using gel permeation chromatography, T. maritima AglA behaved as a dimer (two identical 55-kDa subunits), irrespective of metal depletion or metal addition, and irrespective of the presence or absence of NAD⁺ or DTT. The enzyme hydrolyzes maltose and other small maltooligosaccharides but is inactive against the polymeric substrate starch. AglA is not specific with respect to the configuration at the C-4 position of its substrates because glycosidic derivatives of d-galactose are also hydrolyzed. In the presence of all cofactors, maximum activity was recorded at pH 7.5 and 90°C (4-min assay). AglA is the most thermoactive and the most thermostable member of glycosyl hydrolase family 4. When incubated at 50°C and 70°C, the recombinant enzyme suffered partial inactivation during the first hours of incubation, but thereafter the residual activity did not drop below about 50% and 20% of the initial value, respectively, within a period of 48 h. Received: October 6, 1999 / Accepted: February 9, 2000     

Expression of estrogen receptor (ER) -α and -βtranscripts in the neonatal and adult rat cerebral cortex, cerebellum, and olfactory bulb

INTRODUCTIONEstrogen has been known to exert extensive effects via estrogen receptor (ER) on diverse physio-logical and develoPmental functions of the brain[1,2]. It has been observed that the distribution ofthe classical ER subtype-a (ERa) and the recentlycharacterized novel ER subtype--fi (ERg), and theirexpression patterns (ERcr/ERfi) vary greatly amongvarious brain regions[1, 3]. These evidences suggestthat each ER subtype may play a different role inestrogen's effects on the br…