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Résumé L'effet de la NADH et NAD+ sur la protéolyse de la lacticodéhydrogénase isoenzyme 1 (LDH 1) et isoenzyme 5 (LDH 5) par la trypsine fut étudié. Les résultats montrent que la NAD+ exerce une protection contre la protéolyse de la LDH 1. Mais ni la NADH ni la NAD+ ne protègent contre la protéolyse de la LDH 5. 相似文献
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Summary Female choice mating experiments showed virgin femaleD. melanogaster of the 3Adh genotypes chose heterozygous (Adh
F
/Adh
S
) males most commonly. Inseminated females chose mates randomly, but the likelihood of a female remating was genotypically dependent.Acknowledgment. Financial support was provided by the Australian Research Grants Commitee. 相似文献
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Female choice mating experiments showed virgin female D.melanogaster of the 3 Adh genotypes chose heterozygous (AdhF/AdhS) males most commonly. Inseminated females chose mates randomly, but the likelihood of a female remating was genotypically dependent. 相似文献
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Zinc binding to peptide analogs of the structural zinc site in alcohol dehydrogenase: Implications for an entatic state 总被引:1,自引:0,他引:1
Bergman T Zhang K Palmberg C Jörnvall H Auld DS 《Cellular and molecular life sciences : CMLS》2008,65(24):4019-4027
Zinc binding to the peptide replica and analogs to residues 93–115 of horse liver alcohol dehydrogenase (ADH) was examined
by competition of the peptides and the chromophoric chelator 4-(2- pyridylazo)resorcinol for zinc and X-ray absorption fine
structure analysis of the zinc ligands. In the enzyme, zinc is coordinated by four Cys residues. In the peptide replica, zinc
is bound to three Cys and one His residue. A four-Cys zinc coordination is observed only when His is removed, leading to increased
zinc stability. ADH crystal structures reveal that the ε-amino group of the conserved residue Lys323 is within H-bond distance
of the backbone amide oxygens of residues 103, 105 and 108, likely stabilizing the zinc coordination in the enzyme. The peptide
data thus indicate structural strain and increased energy in the zinc-binding site in the protein, characteristic of an entatic
state, implying a functional nature for this zinc site.
Received 3 July 2008; received after revision 11 August 2008; accepted 1 September 2008 相似文献
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Structure and function of eukaryotic NAD(P)H:nitrate reductase 总被引:7,自引:0,他引:7
Campbell WH 《Cellular and molecular life sciences : CMLS》2001,58(2):194-204
Pyridine nucleotide-dependent nitrate reductases (NRs; EC 1.6.6.1–3) are molybdenum-containing enzymes found in eukaryotic
organisms which assimilate nitrate. NR is a homodimer with an ∼100 kDa polypeptide which folds into stable domains housing
each of the enzyme's redox cofactors—FAD, heme-Fe molybdopterin (Mo-MPT) and the electron donor NAD(P)H—and there is also
a domain for the dimer interface. NR has two active sites: the nitrate-reducing Mo-containing active site and the pyridine
nucleotide active site formed between the FAD and NAD(P)H domains. The major barriers to defining the mechanism of catalysis
for NR are obtaining the detailed three-dimensional structures for oxidized and reduced enzyme and more in-depth analysis
of electron transfer rates in holo-NR. Recombinant expression of holo-NR and its fragments, including site-directed mutagenesis
of key acative site and domain interface residues, are expected to make large contributions to this effort to understand the
catalytic mechanism of NR. 相似文献
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Zusammenfassung Das Ergebnis der immunoelektrophoretischen Untersuchungen zeigt einen gewaltigen Unterschied in den serologischen Mustern der Frösche (Ranidae) und Kröten (Bufonidae). Die amerikanischen Vertreter der Ranidae und der Bufonidae haben sehr wenig gemeinsame Serumantigene. Der Mangel an gemeinsamen antigenischen Bestandteilen in ihren Serumproteinen weist sowohl auf eine frühe Evolutionstrennung des Frosches und der Kröte wie auch auf ein merkliches genetisches Auseinandergehen der zwei Stämme während der langen Zeitspanne isolierter Existenz hin.
The work was supported by grant No. GM-11782 from the U.S. Public Health Service. 相似文献
The work was supported by grant No. GM-11782 from the U.S. Public Health Service. 相似文献
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Remco van Horssen Marieke Willemse Anna Haeger Francesca Attanasio Tuba Güneri Albrecht Schwab Christian M. Stock Roberto Buccione Jack A. M. Fransen Bé Wieringa 《Cellular and molecular life sciences : CMLS》2013,70(12):2175-2190
Oncogenic transformation involves reprogramming of cell metabolism, whereby steady-state levels of intracellular NAD+ and NADH can undergo dramatic changes while ATP concentration is generally well maintained. Altered expression of nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme of NAD+-salvage, accompanies the changes in NAD(H) during tumorigenesis. Here, we show by genetic and pharmacological inhibition of NAMPT in glioma cells that fluctuation in intracellular [NAD(H)] differentially affects cell growth and morphodynamics, with motility/invasion capacity showing the highest sensitivity to [NAD(H)] decrease. Extracellular supplementation of NAD+ or re-expression of NAMPT abolished the effects. The effects of NAD(H) decrease on cell motility appeared parallel coupled with diminished pyruvate-lactate conversion by lactate dehydrogenase (LDH) and with changes in intracellular and extracellular pH. The addition of lactic acid rescued and knockdown of LDH-A replicated the effects of [NAD(H)] on motility. Combined, our observations demonstrate that [NAD(H)] is an important metabolic component of cancer cell motility. Nutrient or drug-mediated modulation of NAD(H) levels may therefore represent a new option for blocking the invasive behavior of tumors. 相似文献
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Teemu Haikarainen Anastassios C. Papageorgiou 《Cellular and molecular life sciences : CMLS》2010,67(3):341-351
Dps-like proteins are key factors involved in the protection of prokaryotic cells from oxidative damage. They act by either
oxidizing iron to prevent the formation of oxidative radicals or by forming Dps-DNA complexes to physically protect DNA. All
Dps-like proteins are characterized by a common three-dimensional architecture and are found as spherical dodecamers with
a hollow central cavity. Despite their structural similarities, recent biochemical and structural data have suggested different
functions among members of the family that range from protection inside the cells in response to various stress signals to
adhesion and virulence during bacterial infections. Moreover, the Dps-like proteins have lately attracted considerable interest
in the field of nanotechnology owing to their ability to act as protein cages for iron and various other metals. A better
understanding of their function and mechanism could therefore lead to novel applications in biotechnology and nanotechnology. 相似文献
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J. B. Gibson A. V. Wilks G. K. Chambers 《Cellular and molecular life sciences : CMLS》1982,38(6):653-654
Summary A 3rd allele at theAdh locus,Adh
FCh.D., has been found at polymorphic frequencies in natural populations ofD. melanogaster. The ADH-FChD enzyme has properties distinct from those of the 2 more common forms of ADH. TheAdh polymorphism should now be analyzed as a triallelic system. 相似文献
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Strömberg P Svensson S Hedberg JJ Nordling E Höög JO 《Cellular and molecular life sciences : CMLS》2002,59(3):552-559
The human alcohol dehydrogenase system is comprised of multiple forms that catalyse the oxidation/reduction of a large variety of alcohols and aldehydes. A transition that results in an Ile308Val substitution was identified in the human ADH2 gene by single-strand conformation polymorphism analysis. Screening a Swedish population revealed that Val308 was the most frequent allele (73%), and site-directed mutagenesis was used to obtain both allelozymes, which were expressed in Escherichia coli for characterisation. Thermostability was assayed by activity measurements and circular dichroism spectroscopy. The results showed that the 308Val substitution decreases protein stability, as compared to the Ile308 variant, an effect also demonstrated during prolonged storage. Ethanol, octanol, 12-hydroxydodecanoic acid and all-trans retinol were used as model substrates and, generally, slightly higher Km values were observed with Val at position 308. Finally, homology modelling, from mouse ADH2, further supported the decreased stability of the Val308 variant and located position 308 in the subunit interface of the molecule and in the vicinity of the active-site pocket entrance. In conclusion, the Ile308Val substitution represents a novel functional polymorphism within the human alcohol dehydrogenase gene cluster that may affect the metabolism of ethanol and other substrates. 相似文献
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The two primary photoreceptor-specific tetraspanins are retinal degeneration slow (RDS) and rod outer segment membrane protein-1
(ROM-1). These proteins associate together to form different complexes necessary for the proper structure of the photoreceptor
outer segment rim region. Mutations in RDS cause blinding retinal degenerative disease in both rods and cones by mechanisms
that remain unknown. Tetraspanins are implicated in a variety of cellular processes and exert their function via the formation
of tetraspanin-enriched microdomains. This review focuses on correlations between RDS and other members of the tetraspanin
superfamily, particularly emphasizing protein structure, complex assembly, and post-translational modifications, with the
goal of furthering our understanding of the structural and functional role of RDS and ROM-1 in outer segment morphogenesis
and maintenance, and our understanding of the pathogenesis associated with RDS and ROM-1 mutations. 相似文献
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Oxidatively damaged biomolecules impair cellular functions and contribute to the pathology of a variety of diseases. RNA is
also attacked by reactive oxygen species, and oxidized RNA is increasingly recognized as an important contributor to neurodegenerative
complications in humans. Recently, evidence has accumulated supporting the notion that tRNA is involved in cellular responses
to various stress conditions. This review focuses on the intriguing consequences of oxidative modification of tRNA at the
structural and functional level. 相似文献
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Ronda Bransteitter Courtney Prochnow Xiaojiang S. Chen 《Cellular and molecular life sciences : CMLS》2009,66(19):3137-3147
The apolipoprotein B mRNA-editing enzyme catalytic polypeptide (APOBEC) family of cytidine deaminases has emerged as an intensively
studied field as a result of their important biological functions. These enzymes are involved in lipid metabolism, antibody
diversification, and the inhibition of retrotransposons, retroviruses, and some DNA viruses. The APOBEC proteins function
in these roles by deaminating single-stranded (ss) DNA or RNA. There are two high-resolution crystal structures available
for the APOBEC family, Apo2 and the C-terminal catalytic domain (CD2) of Apo3G or Apo3G-CD2 [Holden et al. (Nature 456:121–124,
2008); Prochnow et al. (Nature 445:447–451, 2007)]. Additionally, the structure of Apo3G-CD2 has also been determined using
NMR [Chen et al. (Nature 452:116–119, 2008); Furukawa et al. (EMBO J 28:440–451, 2009); Harjes et al. (J Mol Biol, 2009)].
A detailed structural analysis of the APOBEC proteins and a comparison to other zinc-coordinating deaminases can facilitate
our understanding of how APOBEC proteins bind nucleic acids, recognize substrates, and form oligomers. Here, we review the
recent development of structural and functional studies that apply to Apo3G as well as the APOBEC deaminase family. 相似文献
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L. Stankova R. Bigley Sonja R. Wyss H. Aebi 《Cellular and molecular life sciences : CMLS》1979,35(7):852-853
Summary In leukocytes (PMN) of individuals with Swiss type acatalasemia, the rate of dehydroascorbate reduction is 4 times normal. This observation suggests that the protective function served by catalase in human PMN is supported by dehydroascorbate reductase.This work was aided by grants to L.S. and R.B. from the American Cancer Society (CH-30B), the Grand Bethel of Oregon, International Order of Job's Daughters, and to S.W. and H.A. by grant number 3.384.74 from the Swiss National Science Foundation. 相似文献
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Hjelmqvist L Norin A El-Ahmad M Griffiths W Jörnvall H 《Cellular and molecular life sciences : CMLS》2003,60(9):2009-2016
Alcohol dehydrogenases (ADHs) of the MDR type (medium-chain dehydrogenases/reductases) have diverged into two evolutionary groups in eukaryotes: a set of 'constant' enzymes (class III) typical of basal enzymes, and a set of 'variable' enzymes (remaining classes) suggesting 'evolving' forms. The variable set has larger overall variability, different segment variability, and variability also in functional segments. Using a major aldehyde dehydrogenase (ALDH) from cod liver and fish ALDHs deduced from the draft genome sequence of Fugu rubripes (Japanese puffer fish), we found that ALDHs form more complex patterns than the ADHs. Nevertheless, ALDHs also group into 'constant' and 'variable' sets, have separate segment variabilities, and distinct functions. Betaine ALDH (class 9 ALDH) is 'constant,' has three segments of variability, all non-functional, and a limited fish/human divergence, reminiscent of the ADH class III pattern. Enzymatic properties of fish betaine ALDH were also determined. Although all ALDH patterns are still not known, overall patterns are related to those of ADH, and group separations may be distinguished. The results can be interpreted functionally, support ALDH isozyme distinctions, and assign properties to the multiplicities of the ADH and ALDH enzymes. 相似文献