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Author Wilson, M.T.; Ranson, R.J.; Masiakowski, P.; Czarnecka, E.; Brunori, M.
Title A kinetic study of the pH-dependent properties of the ferric undecapeptide of cytochrome c (microperoxidase) Type Journal Article
Year 1977 Publication European Journal of Biochemistry / FEBS Abbreviated Journal Eur J Biochem
Volume 77 Issue 1 Pages 193-199
Keywords Animals; Cyanides; *Cytochrome c Group/metabolism; Ferric Compounds; Horses; Hydrogen-Ion Concentration; Imidazoles; Kinetics; Mathematics; Myocardium/enzymology; *Oligopeptides/metabolism; *Peptide Fragments/metabolism; Protein Binding; Spectrophotometry; Temperature
Abstract The ferric form of the haem undecapeptide, derived from horse cytochrome c by peptic digestion, undergoes at least three pH-induced transitions with pK values of 3.4, 5.8 and 7.6. Temperature-jump experiments suggest that the first of these is due to the binding of a deprotonated imidazole group to the feric iron while the second and third arise from the binding of the two available amino groups present (the alpha-NH2 of valine and the epsilon-NH2 of lysine). Molecular models indicate that steric retraints on the peptide dictate that these amino groups may only coordinate to iron atoms via intermolecular bonds, thus leading to the polymerization of the peptide. Cyanide binding studies are in agreement with these conclusions and also yield a value of 3.6 X 10(6) M-1 s-1 for the intrinsic combination constant of CN- anion with the haem. A model is proposed which describes the pH-dependent properties of the ferric undecapeptide.
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ISSN 0014-2956 ISBN Medium
Area Expedition Conference
Notes PMID:20304 Approved no
Call Number Equine Behaviour @ team @ Serial 3814
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Author Dunn, M.F.; Branlant, G.
Title Roles of zinc ion and reduced coenzyme in horse liver alcohol dehydrogenase catalysis. The mechanism of aldehyde activation Type Journal Article
Year 1975 Publication Biochemistry Abbreviated Journal Biochemistry
Volume 14 Issue 14 Pages 3176-3182
Keywords *Alcohol Oxidoreductases/metabolism; Aldehydes/*pharmacology; Animals; Binding Sites; Enzyme Activation/drug effects; Horses; Hydrogen-Ion Concentration; Kinetics; Liver/enzymology; *NAD/analogs & derivatives/pharmacology; Oxidation-Reduction; Protein Binding; Spectrophotometry; Spectrophotometry, Ultraviolet; Temperature; *Zinc/pharmacology
Abstract 1,4,5,6-Tetrahydronicotinamide adenine dinucleotide (H2NADH) has been investigated as a reduced coenzyme analog in the reaction between trans-4-N,N-dimethylaminocinnamaldehyde (I) (lambdamax 398 nm, epsilonmax 3.15 X 10-4 M-minus 1 cm-minus 1) and the horse liver alcohol dehydrogenase-NADH complex. These equilibrium binding and temperature-jump kinetic studies establish the following. (i) Substitution of H2NADH for NADH limits reaction to the reversible formation of a new chromophoric species, lambdamax 468 nm, epsilonmax 5.8 x 10-4 M-minus 1 cm-minus 1. This chromophore is demonstrated to be structurally analogous to the transient intermediate formed during the reaction of I with the enzyme-NADH complex [Dunn, M. F., and Hutchison, J. S. (1973), Biochemistry 12, 4882]. (ii) The process of intermediate formation with the enzyme-NADH complex is independent of pH over the range 6.13-10.54. Although studies were limited to the pH range 5.98-8.72, a similar pH independence appears to hold for the H2NADH system. (iii) Within the ternary complex, I is bound within van der Waal's contact distance of the coenzyme nicotinamide ring. (iv) Formation of the transient intermediate does not involve covalent modification of coenzyme. Based on these findings, we conclude that zinc ion has a Lewis acid function in facilitating the chemical activation of the aldehyde carbonyl for reduction, and that reduced coenzyme plays a noncovalent effector role in this substrate activating step.
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ISSN 0006-2960 ISBN Medium
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Notes PMID:238585 Approved no
Call Number Equine Behaviour @ team @ Serial 3817
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Author Wilson, M.T.; Silvestrini, M.C.; Morpurgo, L.; Brunori, M.
Title Electron transfer kinetics between Rhus vernicifera stellacyanin and cytochrome c (horse heart cytochrome c and Pseudomonas cytochrome c551) Type Journal Article
Year 1979 Publication Journal of Inorganic Biochemistry Abbreviated Journal J Inorg Biochem
Volume 11 Issue 2 Pages 95-100
Keywords Animals; Copper; Cytochrome c Group/*metabolism; Electron Transport; Kinetics; Metalloproteins/*metabolism; Plant Proteins/*metabolism; *Plants, Toxic; Pseudomonas aeruginosa/*metabolism; Toxicodendron/*metabolism
Abstract The electron transfer reactions between Rhus vernicifera stellacyanin and either horse heart cytochrome c or Pseudomonas aeruginosa cytochrome c551 were investigated by rapid reaction techniques. The time course of electron transfer is monophasic under all conditions, and thus consistent with a simple formulation of the reaction. Both stopped-flow and temperature-jump experiments yield equilibrium constants in reasonable agreement with values calculated from the redox potentials. The differences in reaction rate between the two cytochromes and stellacyanin are discussed in terms of the Marcus theory.
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Language English Summary Language Original Title
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ISSN 0162-0134 ISBN Medium
Area Expedition Conference
Notes PMID:228006 Approved no
Call Number refbase @ user @ Serial 3879
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Author Czerlinski, G.H.; Wagner, M.; Erickson, J.O.; Theorell, H.
Title Chemical relaxation studies on the system liver alcohol dehydrogenase, NADH and imidazole Type Journal Article
Year 1975 Publication Acta Chemica Scandinavica. Series B: Organic Chemistry and Biochemistry Abbreviated Journal Acta Chem Scand B
Volume 29 Issue 8 Pages 797-810
Keywords Alcohol Oxidoreductases/*metabolism; Animals; Computers; Hydrogen-Ion Concentration; Imidazoles/*metabolism; Kinetics; Liver/enzymology/*metabolism; Mathematics; Models, Chemical; NAD/*metabolism; Time Factors
Abstract Several years ago, Theorell and Czerlinski conducted experiments on the system of horse liver alcohol dehydrogenase, reduced nicotinamide adenine dinucleotide and imidazole, using the first version of the temperature jump apparatus with detection of changes in fluorescence. These early experiments were repeated with improved instrumentation and confirmed the early experiments in general terms. However, the improved detection system allowed to measure a slight concentration dependence of the relaxation time of around 3 ms. Furthermore, the chemical relaxation time was smaller than the one determined earlier (by factor 2). The data were evaluated much more rigorously than before, allowing an appropriate interpretation of the results. The observed relaxation time is largely due to rate constants in an interconversion of ternary complexes, which are faster than three (of the four) dissociation rate constants, determined previously by Theorell and McKinley-McKee.1,2 This fact contributed to earlier difficulties of finding any concentration dependence. However, the binding of imidazole to the binary enzyme-coenzyme complex can be made to couple kinetically into the interconversion rate of the two ternary complexes. The observed signal derives largely from the ternary complex(es). A substantial fluorescence signal change is associated with the observed relaxation process, suggesting a relocation of the imidazole in reference to the nicotinamide moiety of the bound coenzyme. Nine models are considered with two types of coupling of pre-equilibria (none-all). Quantitative evaluations favor the model with two ternary complexes connected by an interconversion outside the four-step (bimolecular) cycle. The ternary complex outside the cycle has much higher fluorescence yield than the one inside. The interconversion equilibrium is near unity for imidazole. If it would be shifted very much to the side of the “dead-end” complex (as in isobutyramide?!), stimulating action could not take place.
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ISSN 0302-4369 ISBN Medium
Area Expedition Conference
Notes PMID:882 Approved no
Call Number refbase @ user @ Serial 3887
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Author Andersen, N.H.; Norgaard, A.; Jensen, T.J.; Ulstrup, J.
Title Sequential unfolding of the two-domain protein Pseudomonas stutzeri cytochrome c4 Type Journal Article
Year 2002 Publication Journal of Inorganic Biochemistry Abbreviated Journal
Volume 88 Issue 3-4 Pages 316-327
Keywords P. stutzeri cytochrome c4; Sequential unfolding; Di-haem protein; Unfolding
Abstract P. stutzeri cytochrome c4 is a di-haem protein, composed of two globular domains each with His-Met coordinated haem, and a hydrogen bond network between the domains. The domain foldings are highly symmetric but with specific differences including structural differences of ligand coordination, and different spin states of the oxidised haem groups. We have studied unfolding of oxidised P. stutzeri cyt c4 induced thermally and by chemical denaturants. Horse heart cyt c was a reference molecule. Isothermal unfolding induced by guanidinium chloride and acid was followed by Soret, α/β, and 701-nm band absorption, and by far-UV circular dichroism spectroscopy. Multifarious patterns emerge, but the two domains clearly unfold sequentially. One phase, assigned to unfolding of the N-terminal domain, proceeds at guanidinium concentrations up to [approximate]1.0 M. This is followed by two overlapping phases at higher concentrations. The intermediate state maintains Fe-Met coordination, assigned to the C-terminal domain. Interdomain interaction is reflected in decreasing values of the cooperativity parameters. Differential scanning calorimetry shows a single peak, but two peaks appear when guanidinium chloride up to 0.4 M is present. This reflects different chemical action in chemical and thermal unfolding. Acid-induced unfolding kinetics was addressed by pH jumps using diode array stopped-flow techniques. Three kinetic phases in the 701 nm Fe-Met marker band, and four phases in the Soret and α/β bands, spanning 4-1000 ms could be distinguished on pH jumps from 7.5 to the range 2.5-3.5. In this range of time and pH cyt c appears to unfold in no more than two phases. Spectral properties of the kinetic intermediates could be identified. Sequential domain unfolding, formation of high-spin states, and an intermediate state with Fe-Met coordination to a single haem group are features of the unfolding kinetics.
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Notes Approved no
Call Number refbase @ user @ Serial 3973
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Author Kordal, R.J.; Parsons, S.M.
Title Liver alcohol dehydrogenase subunit equivalence studied by rapid sampling of alcohol product formed from sequentially bound [4α-3H]NADH Type Journal Article
Year 1979 Publication Archives of Biochemistry and Biophysics Abbreviated Journal
Volume 194 Issue 2 Pages 439-448
Keywords
Abstract Horse liver alcohol dehydrogenase has been claimed to exhibit presteady-state “half-of-the-sites” reactivity with aromatic substrates under some circumstances. To clarify the role of half-of-the-sites reactivity in liver alcohol dehydrogenase the direct sampling of the alcohol product formed immediately after initiation of the reaction was studied using a rapid sampling device and [4α-3H]NADH. Liver alcohol dehydrogenase which contained a very low mole-ratio of [4α-3H]NADH bound to one subunit of the dimer was rapidly mixed with excess 4-(2'-imidazolylazo)benzaldehyde substrate and nonradioactive NADH to initiate the reaction, which was allowed to proceed for a short time before it was quenched. If strong HClO4 quench was used isolation of total free and bound azoalcohol product was possible. If NaOH quench was used isolation only of the azoalcohol product released by the enzyme was possible since most enzyme-bound azoalcohol was reversed back to azoaldehyde by the base. The pH-jump reversal reaction also was characterized spectroscopically by stopped flow technique. Nearly fullsites reactivity was observed for reaction in either direction. Furthermore (4α-3H]NADH bound firstly to one subunit in the dimer reacted essentially identically to NADH bound secondly to the other subunit. Thus, half-of-the-sites reactivity was not observed in these experiments nor did they give any indication of liver alcohol dehydrogenase active site nonequivalence induced by coenzyme binding or reaction.
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Notes Approved no
Call Number refbase @ user @ Serial 3983
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Author Wood, F.E.; Cusanovich, M.A.
Title The reaction of Euglena gracilis cytochrome c-552 with nonphysiological oxidants and reductants Type Journal Article
Year 1975 Publication Archives of Biochemistry and Biophysics Abbreviated Journal
Volume 168 Issue 2 Pages 333-342
Keywords
Abstract The reaction of Euglena gracilis cytochrome c-552 (cytochrome f) with the nonphysiological reactants potassium ferrocyanide, potassium ferricyanide, sodium ascorbate, sodium dithionite, and Chromatium vinosum high potential nonheme iron protein was studied by stopped-flow and temperature-jump kinetic methods. The reaction of the purified, water-soluble protein with the reactants was investigated as a function of ionic strength, pH, and temperature. The results demonstrated that reduction and oxidation takes place at a negatively charged site on the cytochrome c-552 surface. Participation of specific amino acid residues in electron transfer is implicated from the pH results. The results obtained for the nonphysiological reactions of cytochrome c-552 are compared with available data for horse heart cytochrome c and Rhodospirillum rubrum cytochrome c2. The results strongly suggest that Euglena gracilis cytochrome c-552 undergoes nonphysiological oxidation and reduction by a mechanism different from that found for cytochrome c or cytochrome c2.
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Call Number refbase @ user @ Serial 3987
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Author Matzke, S.M.; Oubre, J.L.; Caranto, G.R.; Gentry, M.K.; Galbicka, G.
Title Behavioral and immunological effects of exogenous butyrylcholinesterase in rhesus monkeys Type Journal Article
Year 1999 Publication Pharmacology, Biochemistry, and Behavior Abbreviated Journal Pharmacol Biochem Behav
Volume 62 Issue 3 Pages 523-530
Keywords Animals; Antibody Formation/drug effects; Behavior, Animal/*drug effects; Butyrylcholinesterase/*immunology/pharmacokinetics/*pharmacology; Cognition/drug effects; Color Perception/drug effects; Conditioning, Operant/drug effects; Discrimination Learning/drug effects; Half-Life; Horses; Humans; Macaca mulatta; Male
Abstract Although conventional therapies prevent organophosphate (OP) lethality, laboratory animals exposed to such treatments typically display behavioral incapacitation. Pretreatment with purified exogenous human or equine serum butyrylcholinesterase (Eq-BuChE), conversely, has effectively prevented OP lethality in rats and rhesus monkeys, without producing the adverse side effects associated with conventional treatments. In monkeys, however, using a commercial preparation of Eq-BuChE has been reported to incapacitate responding. In the present study, repeated administration of commercially prepared Eq-BuChE had no systematic effect on behavior in rhesus monkeys as measured by a six-item serial probe recognition task, despite 7- to 18-fold increases in baseline BuChE levels in blood. Antibody production induced by the enzyme was slight after the first injection and more pronounced following the second injection. The lack of behavioral effects, the relatively long in vivo half-life, and the previously demonstrated efficacy of BuChE as a biological scavenger for highly toxic OPs make BuChE potentially more effective than current treatment regimens for OP toxicity.
Address Walter Reed Army Institute of Research, Washington, DC 20307-5100, USA
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ISSN 0091-3057 ISBN Medium
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Notes PMID:10080246 Approved no
Call Number Equine Behaviour @ team @ Serial 4064
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Author Choleris, E.; Kavaliers, M.
Title Social Learning in Animals: Sex Differences and Neurobiological Analysis Type Journal Article
Year 1999 Publication Pharmacology Biochemistry and Behavior Abbreviated Journal Pharmacol. Biochem. Behav.
Volume 64 Issue 4 Pages 767-776
Keywords Observational learning; Social learning; Individual learning; Imitation; Social constraints; Social facilitation; male-female differences; Gender differences
Abstract Social learning where an “individual's behavior is influenced by observation of, or interaction with, another animal or its products” has been extensively documented in a broad variety of species, including humans. Social learning occurs within the complex framework of an animal's social interactions that are markedly affected by factors such as dominance hierarchies, family bonds, age, and sex of the interacting individuals. Moreover, it is clear that social learning is influenced not only by important sexually dimorphic social constraints but also that it involves attention, motivational, and perceptual mechanisms, all of which exhibit substantial male-female differences. Although sex differences have been demonstrated in a wide range of cognitive and behavioral processes, investigations of male-female differences in social learning and its neurobiological substrates have been largely neglected. As such, sex differences in social learning and its neurobiological substrates merit increased attention. This review briefly considers various aspects of the study of social learning in mammals, and indicates where male-female differences have either been described, neglected and, or could have a potential impact. It also describes the results of neurobiological investigations of social learning and considers the relevance of these findings to other sexually dimorphic cognitive processes.
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Notes Approved no
Call Number refbase @ user @ Serial 575
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Author Bigiani, A.; Mucignat-Caretta, C.; Montani, G.; Tirindelli, R.
Title Pheromone reception in mammals Type Journal Article
Year 2005 Publication Reviews of Physiology, Biochemistry and Pharmacology Abbreviated Journal
Volume 154 Issue Pages 1-35
Keywords
Abstract Pheromonal communication is the most convenient way to transfer information regarding gender and social status in animals of the same species with the holistic goal of sustaining reproduction. This type of information exchange is based on pheromones, molecules often chemically unrelated, that are contained in body fluids like urine, sweat, specialized exocrine glands, and mucous secretions of genitals. So profound is the relevance of pheromones over the evolutionary process that a specific peripheral organ devoted to their recognition, namely the vomeronasal organ of Jacobson, and a related central pathway arose in most vertebrate species. Although the vomeronasal system is well developed in reptiles and amphibians, most mammals strongly rely on pheromonal communication. Humans use pheromones too; evidence on the existence of a specialized organ for their detection, however, is very elusive indeed. In the present review, we will focus our attention on the behavioral, physiological, and molecular aspects of pheromone detection in mammals. We will discuss the responses to pheromonal stimulation in different animal species, emphasizing the complicacy of this type of communication. In the light of the most recent results, we will also discuss the complex organization of the transduction molecules that underlie pheromone detection and signal transmission from vomeronasal neurons to the higher centers of the brain. Communication is a primary feature of living organisms, allowing the coordination of different behavioral paradigms among individuals. Communication has evolved through a variety of different strategies, and each species refined its own preferred communication medium. From a phylogenetic point of view, the most widespread and ancient way of communication is through chemical signals named pheromones: it occurs in all taxa, from prokaryotes to eukaryotes. The release of specific pheromones into the environment is a sensitive and definite way to send messages to other members of the same species. Therefore, the action of an organism can alter the behavior of another organism, thereby increasing the fitness of either or both. Albeit slow in transmission and not easily modulated, pheromones can travel around objects in the dark and over long distances. In addition, they are emitted when necessary and their biosynthesis is usually economic. In essence, they represent the most efficient tool to refine the pattern of social behaviors and reproductive strategies. © Springer-Verlag 2005.
Address Università di Parma, Dipartimento di Neuroscienze, Sezione di Fisiologia, Via Volturno 39, 43100 Parma, Italy
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Call Number Equine Behaviour @ team @ Serial 4570
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