Beef liver glutamate dehydrogenase: A study of the oxidation of various alternative amino acid substrates retaining the correct spacing of the two carboxylate groups

• 1.1. Several glutamate analogues substituted at the β- or γ-carbon atoms have been tested as substrates for glutamate dehydrogenase.
• 2.2. The two γ-methyl derivatives and DL-β-methylglutamate give the same pH optimum (8.7) as l-glutamate, but show inhibition by ADP and activation by GTP at pH 8, unlike glutamate and like the monocarboxylic substrate l-norvaline, which gives a pH optimum of 10.
• 3.3. l-γ-methyleneglutamate, the poorest substrate tested (0.28% of rate with glutamate) gives a high pH optimum (10), like norvaline, but shows marked activation by both ADP (13-fold) and GTP (27-fold).
• 4.4. Despite the correct dicarboxylate spacing, all the analogues were much poorer substrates than l-norvaline.

     

Interaction of proteins located at a distance along DNA: mechanism of target immunity in the Mu DNA strand-transfer reaction

DNA molecules carrying a Mu end(s) are inefficient targets in the Mu DNA strand-transfer reaction. This target immunity is due to preferential dissociation of Mu B protein from DNA molecules that have Mu A protein bound to the Mu end; free DNA is a much poorer target than DNA with Mu B protein bound. We show that Mu B protein, which binds nonspecifically to DNA, is immobile once bound. An encounter between Mu A and Mu B proteins, bound some distance apart along DNA, is necessary to facilitate the Mu B dissociation. Experiments which show that DNA without a Mu end can acquire immunity, by catenation to DNA with a Mu end(s), are consistent with a model of Mu A-Mu B interaction by DNA looping, but not by linear movement of protein(s) along DNA.     

Predictors and correlates of edentulism in the healthy old people in Edinburgh (HOPE) study

Objectives: To determine the extent to which correlates of edentulism are explained by an association between tooth loss and cognitive ability. Methods: Participants in the Healthy Old People in Edinburgh (HOPE) study aged 70 or more at baseline were assessed and health, cognitive, socio‐economic and socio‐environmental data collected on four consecutive occasions. It was noted whether the participant had any retained teeth and if not, the age when the last tooth was lost. Prior determinants of edentulism were investigated with binary logistic regression models. At the 9‐year follow‐up, associations with edentulism were examined using general linear models with edentulism as an independent factor. Results: 201 participants were adequately tested, of whom 104 (51.7%) were edentulous. A logistic regression model that considered age, sex, education, social class, deprivation index of residence, objective distance from dentist, participant’s estimate of distance from dentist and NART‐estimated IQ (NARTIQ) found age (p = 0.032), occupational class (p = 0.019) and NARTIQ (p = 0.027) as significant predictors of edentulism. Cox’s proportional hazards modelling found only NARTIQ (p = 0.050) to be correlated. Being edentulous was associated with poorer respiratory function but not hand grip strength (p = 0.23). Edentulous participants had lower self esteem scores (p = 0.020) and poorer dietary assessment scores (p = 0.028). Being edentulous was also associated with significantly lower mean scores on all cognitive testing, although these associations became non‐significant after adjustment for NARTIQ and age. Conclusions: In healthy older people, edentulism is associated with relative impairment of cognitive ability, although this association is explained by the fact that lower original intelligence predisposes to edentulism and poorer performance on cognitive tests in old age. Once original intelligence is adjusted for, tooth loss is not related to cognitive ability. Tooth loss is, however, associated with poorer status across a wide range of health measures: physical health, nutrition, disability and self‐esteem. Establishing the degree to which these health outcomes are causally related to edentulism could usefully be factored into cost–benefit analyses of programmes designed to prevent tooth loss.     

Ester hydrolysis with 2,6-di(pyrazol-3-yl)pyridines and their CoII complexes in homogeneous and micellar media

The 1:1 complex of Co(ClO4)2 with the H2O-insoluble tridentate 2,6-di(1H-4,5,6,7-tetrahydroindazol-3-yl)pyridine (H21) was found to be an excellent catalyst for the hydrolysis of para-nitrophenyl acetate in aqueous buffers over the pH 7.05-7.90 range, with an estimated second-order rate constant of 0.50 M(-1) s(-1). The Co2+ complexes of the N,N'-di-1-dodecyl analogue in micellar media and the N,N'-di-(4-carboxyphenyl) analogue in aqueous media were much poorer catalysts, poorer than the free ligands. In all cases, the pH-rate profiles indicated that free base, deprotonated or hydroxo forms were the active species. The greater success with Co(H(2)1)2+ indicated a catalytic role for N-H deprotonation.     

Malonyl-coenzyme A:isoflavone 7-O-glucoside-6"-O-malonyltransferase from roots of chick pea (Cicer arietinum L.)

A malonyltransferase which catalyzes the malonylation of isoflavone 7-O-glucosides in position 6 of the glucose moiety using malonyl-coenzyme A as acyl donor has been purified 157-fold from 4-day-old roots of chick pea (Cicer arietinum L.). The enzyme showed a pH optimum of 8.0 and a molecular weight of 112,000. The Km for malonylcoenzyme A was 48 microM and, for the chick pea isoflavones biochanin A and formononetin, 36 and 24 microM, respectively. Various other isoflavone, flavone, and flavonol 7-O-glucosides and chalcone 4'-O-glucosides were much poorer substrates. Flavonol 3-O-glucosides and isoflavone 4'-O-glucosides were not malonylated by the malonyltransferase.     

Synthesis and reactivity with beta-lactamases of a monobactam bearing a retro-amide side chain

The monobactam sodium 3-benzylcarbamoyl-2-oxo-1-azetidinesulfonate, bearing a retro (vs classical beta-lactam)-amide side chain, has been synthesized and the kinetics of its reaction with typical beta-lactamases studied. The new compound is generally a poorer substrate than the analogous compound with a normal side chain but its formation of a transiently stable complex with a class C beta-lactamase sustains the retro-amide side-chain concept.     

Studies of the in vitro oxidation of 1-methyl-4-(1-methylpyrrol-2-yl)-4-piperidinol and its dehydration product 1,2,3,6-tetrahydro-1-methyl-4-(methylpyrrol-2-yl) pyridine by human monoamine oxidases A and B

The ability of highly purified preparations of human monoamine oxidase A and B (MAO A and B) to utilize 1-methyl-4-(1-methylpyrrol-2-yl)-4-piperidinol (MMPP) and its dehydration product 1,2,3,6-tetrahydro-1-methyl-4-(methylpyrrol-2-yl) pyridine (TMMP) as substrates was investigated. The results showed that TMMP was a substrate for both forms of MAO with Km,app values of approximately 60 microM. However, MAO B had a Vmax,app for TMMP about 30-fold greater than MAO A. Additional studies revealed that MMPP was a poor substrate of only MAO B (Km,app = 9.5 mM) and that acid treatment of MMPP led to the formation of a product that could be readily oxidized by both MAO A and B. Similar acid pretreatment of TMMP yielded a product that was a much poorer substrate for MAO B than the parent compound. These results may partially explain why orally administered MMPP produces neurotoxicity in monkeys and TMMP fails to induce chemical parkinsonism.     

AbrB modulates expression and catabolite repression of a Bacillus subtilis ribose transport operon.

A Bacillus subtilis ribose transport operon (rbs) was shown to be subject to AbrB-mediated control through direct AbrB-DNA binding interactions in the vicinity of the promoter. Overproduction of AbrB was shown to relieve catabolite repression of rbs during growth in the presence of poorer carbon sources such as arabinose but had much less effect when cells were grown in the presence of glucose, a rapidly metabolizable carbon source. A ccpA mutation relieved catabolite repression of rbs under all conditions tested. One of the AbrB-binding sites on the rbs promoter contains the putative site of action for the B. subtilis catabolite repressor protein CcpA, suggesting that competition for binding to this site could be at least partly responsible for modulating rbs expression during carbon-limited growth.     

Trifluoromethyl ketones and methyl fluorophosphonates as inhibitors of group IV and VI phospholipases A(2): structure-function studies with vesicle, micelle, and membrane assays.

A series of fatty alkyl trifluoromethyl ketones and methyl fluorophosphonates have been prepared and tested as inhibitors and inactivators of human groups IV and VI phospholipases A(2) (cPLA(2) and iPLA(2)). Compounds were analyzed with phospholipid vesicle-, detergent-phospholipid mixed-micelle-, and natural membrane-based assays, and, with few exceptions, the relative inhibitor potencies measured with the three assays were similar. Ph(CH(2))(4)COCF(3) and Ph(CH(2))(4)PO(OMe)F emerged as a potent inhibitor and inactivator, respectively, of iPLA(2), and both are poorly effective against cPLA(2). Of all 13 fatty alkyl trifluoromethyl ketones tested, the trifluoromethyl ketone analog of arachidonic acid is the most potent cPLA(2) inhibitor, and structurally similar compounds including the trifluoromethyl ketone analog of docosahexenoic acid are much poorer cPLA(2) inhibitors. Inactivation of cPLA(2) by fatty alkyl fluoromethylphosphonates is greatly promoted by binding of enzyme to the interface. The use of both vesicles and mixed micelles to assay phospholipase A(2) inhibitors and inactivators present at low mol fraction in the interface provides reliable rank order potencies of a series of compounds that correlate with their behavior in a natural membrane assay.     

Effects of Cardiac Glycosides on Electrical Activity in the Isolated Retina of the Frog

Ouabain added to physiological salt solutions bathing the isolated frog retina irreversibly abolishes the electrical response to light (the electroretinogram or ERG). The time course of abolition depends on the concentration of ouabain in the medium and the surface of the retina to which it is applied. When the glycoside is placed on the receptor surface, in 7 min the ERG is completely eliminated by 10^-4 M ouabain and more than 90% inhibited by 3 x 10^-5 M ouabain. The effect is slower at lower concentrations and when the solution is applied to the vitreous surface of the retina. The evidence suggests that abolition of the ERG by ouabain is due principally to inhibition of the active transport of sodium: (a) Structurally modified glycosides which are considerably less potent inhibitors of alkali cation-activated ATPase activity in preparations of frog retinal outer segments are also poorer inhibitors of electrical activity in isolated retinas. (b) Replacing much of the sodium in the medium bathing the retina by choline, Tris, or sucrose significantly protects the retina from ouabain. It is suggested that in a standard sodium environment essentially constant activity of the sodium pump is required to prevent rapid and irreversible change. The cellular sites most critically dependent on the sodium pump have not been identified.     

Structure and Function of sanV: a gene involved in nikkomycin biosynthesis of Streptomyces ansochromogenes

A 6.3-kb BamHI- BglII DNA fragment was cloned from cos20 by using chromosome walking strategy. It was partially sequenced with the result that there is a possible ORF of 1272 nucleotides. The ORF designated sanV was deposited in GenBank under accession no. AF469955. Database search indicated that the deduced protein of sanV shows 28% identity and 44% similarity over 405 amino acid residues to the large component (E) of glutamate mutases from Clostridium cochlearium. Gene disruption was performed to study the function of sanV. It was found that sanV disruptants exhibited much poorer inhibition to the test strain than the wild-type S. ansochromogenes 7100. Furthermore, HPLC analysis indicated that the sanV disruptants almost did not produce nikkomycins X and Z, whereas they accumulated new nikkomycins O(x) and O(z), which revealed that sanV is an important gene involved in the biosynthesis of the peptidyl moiety of nikkomycins.     

Submandibular gland tumors.

Tumors involving the submandibular gland are rare. However, the incidence of malignancy is much higher than in the parotid (approaching 50 percent). In addition, the 5-year survival rate in patients with malignant tumors of the submandibular gland is much poorer in our series--28 percent versus 71.8 percent for the parotid gland. Because of the poor prognosis in patients with malignant tumors involving the submandibular gland we feel that composite resections should be carried out for all tumors except low-grade mucoepidermoid tumors. In addition, postoperative radiation should be given for specific indications (detailed in the article).     

The effect of cultivation system and soil factors on the performance of herbicides against Alopecurus myosuroides

Aspects of chemical and cultural control of Alopecurus myosuroides (blackgrass) in winter wheat were studied on a naturally-occurring infestation over a 3-yr period. In two experiments a comparison was made between ploughing and direct drilling, whilst in the third experiment direct drilling alone was used. Straw was spread and burnt in each year. Herbicide treatments were: chlortoluron and isoproturon in all three experiments; diclofop-methyl and pendimethalin in two experiments; metoxuron, terbutryne, tri-allate, carbetamide, propyzamide, chlorsulfuron + methabenthiazuron and trifluralin + linuron in one experiment. Herbicides were applied either pre-emergence, early post-emergence or late postemergence to separate sub-plots. Surface soil (0–2.5 cm) samples were collected each year from unsprayed areas and used for soil analyses and for herbicide activity studies in pot experiments. Ploughing resulted in much lower populations of A. myosuroides than direct drilling. Most herbicides gave much better control of A. myosuroides in ploughed than in direct drilled soil in field and pot experiments, regardless of application time. Diclofop-methyl, applied early post-emergence at 1.13 kg a.i./ha, was the only herbicide treatment in field experiments to achieve over 90% weed control in direct drilled soil. Differences in adsorption between soils given different cultivations, determined as Kd values for chlortoluron and isoproturon, were much greater than differences in organic matter. The much greater adsorptive capacity of direct drilled soil, and consequently the poorer performance of all soil-acting herbicides, was attributed to the concentration of burnt straw residues near the soil surface.     

The low level of differences between mitogenomes of the Sakhalin sturgeon <Emphasis Type="Italic">Acipenser mikadoi</Emphasis> Hilgendorf, 1892 and the green sturgeon <Emphasis Type="Italic">A. medirostris</Emphasis> Ayeres, 1854 (Acipenseridae) indicates their recent divergence

The complete mitochondrial genome of the Sakhalin sturgeon Acipenser mikadoi and two mitogenomes of the Amur sturgeon A. schrenckii were sequenced using Roche 454 technology. The mitogenomes of the green sturgeon A. medirostris (obtained from GenBank) and the Sakhalin sturgeon differ as much as the mitogenomes of two mtDNA haplogroups (SM and BG) found in the same population of the Amur sturgeon: 0.0042 ± 0.0006 and 0.0036 ± 0.0005 substitutions per site (Tamura–Nei distance, TrN), respectively. The differences of these mitogenome pairs from mitogenomes of sister species (kaluga A. dauricus and white sturgeon A. transmontanus) are 3–6 times larger: 0.0260 ± 0.0015 and 0.0102 ± 0.0008, respectively. Thus, the differences between the mitogenomes of the Sakhalin and green sturgeons can be attributed to the variability at the intraspecific level. The time that has passed since the divergence of the Sakhalin and green sturgeons is considered to be much shorter than was previously believed: approximately 0.16 rather than 9.60 million years.     

A230Y mutation of actin on subdomain 4 is sufficient for higher calcium activation of actin-activated myosin adenosinetriphosphatase in the presence of tropomyosin-troponin

To probe the mechanism by which Ca(2+) activates muscle contraction through tropomyosin and troponin, we have produced mutant actins using Dictyostelium discoideum. We focused on the sequence 228-232 (QTAAS) that is located in subdomain 4 of actin, because the chimera actin in which this sequence was replaced by KAYKE showed not only poorer tropomyosin binding but also the unexpected "higher Ca(2+) activation" [Saeki, K., et al. (1996) Biochemistry 35, 14465-14472]. We found that this higher Ca(2+) activation is solely due to the A230Y mutagenesis. Because A230Y mutant actin showed normal tropomyosin binding, the higher Ca(2+) activation is not the consequence of poorer tropomyosin binding. The significance of these results is discussed in view of a three-state model [McKillop, D. F., Geeves, M. A. (1993) Biophys. J. 65, 693-701].     

Chemically Exfoliating Biomass into a Graphene‐like Porous Active Carbon with Rational Pore Structure,Good Conductivity,and Large Surface Area for High‐Performance Supercapacitors

Active carbons have unique physicochemical properties, but their conductivities and surface to weight ratios are much poorer than graphene. A unique and facile method is innovated to chemically process biomass by “drilling” holes with H₂O₂ and exfoliating into graphene‐like nanosheets with HAc, followed by carbonization at a high temperature for highly graphitized activated carbon with greatly enhanced porosity, unique pore structure, high conductivity, and large surface area. This graphene‐like carbon exhibits extremely high specific capacitance (340 F g^?1 at 0.5 A g^?1) and high specific energy density (23.33 to 16.67 W h kg^?1) with excellent rate capability and long cycling stability (remains 98% after 10 000 cycles), which is much superior to all reported carbons including graphene. Synthesis mechanism for deriving biomass into porous graphene‐like carbons is discussed in detail. The enhancement mechanism for the porous graphene‐like carbon electrode reveals that rationally designed meso‐ and macropores are very critical in porous electrode performance, which can network micropores for diffusion freeways, high conductivity, and high utilization. This work has universal significance in producing highly porous and conductive carbons from biomass including biowastes for various energy storage/conversion applications.     

Social class,non-employment,and chronic illness: continuing the inequalities in health debate.

The 1981-2 General Household Survey showed steep class gradients in limiting longstanding illness for men and women aged 20-59 that were very similar to the class gradients in mortality in the 1979-83 decennial supplement. The class gradient for women classified by their husband''s occupation was stronger than that when they were classified by their own occupation. Men and women who lacked paid employment reported poorer health than the employed and were concentrated in the lower social classes. Inequalities in ill health due to class were partly caused by the higher proportion in the lower social classes who were without work. Class differences in ill health still existed, however, among the currently employed, with unskilled men reporting particularly poor health and women manual workers reporting poorer health than women in non-manual jobs. Class differences were greater for the occupationless than for the currently employed. Thus class remains an important indicator of health inequalities despite the current high level of unemployment.     

Increased expression of the gene encoding stearoyl-CoA desaturase 1 in human bladder cancer

Bladder cancer is a common disease and a significant cause of death worldwide. There is thus great interest in identifying a diagnostic and prognostic biomarker, as well as gaining an understanding of the molecular basis of bladder cancer. Stearoyl-CoA desaturase 1 gene (SCD1) is highly overexpressed in many human cancers. However, the expression of SCD1 has not yet been investigated in patients with bladder cancer. Here, we document that (a) the SCD1 is highly overexpressed in human bladder cancer; (b) high expression of SCD1 is more frequently observed in the late stage of disease and patients with lymph node metastasis; (c) bladder cancer patients with a higher SCD1 mRNA level have a poorer survival rate than those with normal SCD1 expression. Overall, this is the first report to indicate an association between SCD1 mRNA level and clinical indicators of human bladder cancer. Our study has provided evidence supporting the potential role of SCD1 as a biomarker for human bladder cancer prognosis.     

Ancient Interlocus Exon Exchange in the History of the Hla-a Locus

The major histocompatibility complex (MHC) in humans and chimpanzees includes three classical class I loci, A, B and C, which encode glycoproteins expressed on the surface of all nucleated cells. There are also several nonclassical class I loci including E, which have more limited expression. By analyzing published sequences, we have shown that in exons 4 and 5, A locus alleles from both humans and chimpanzees are much more similar to E than to B or C alleles, whereas in exons 2 and 3 alleles from all three classical class I loci are much more similar to each other than any one is to E. We propose that some 20 million years ago, interlocus recombination led to the formation of a hybrid gene in which exons 2 and 3 were derived from the original A locus and exons 4 and 5 were derived from the E locus. The fact that such an ancient event can still be detected suggests that interlocus recombination is rare in the MHC and does not significantly contribute to MHC polymorphism, which is known to be extremely high. The present finding, however, supports Gilbert's idea that exons in a gene may occasionally be replaced by those from another gene in the evolutionary process.