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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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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
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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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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
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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 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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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
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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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Author Brown, R.F.; Houpt, K.A.; Schryver, H.F.
Title Stimulation of food intake in horses by diazepam and promazine Type Journal Article
Year 1976 Publication Pharmacology, biochemistry, and behavior Abbreviated Journal Pharmacol Biochem Behav
Volume 5 Issue 4 Pages 495-497
Keywords Age Factors; Animals; Diazepam/*pharmacology; Diet; Feeding Behavior/*drug effects; Female; Horses/*physiology; Male; Promazine/*pharmacology; Stimulation, Chemical
Abstract In two adult horses doses of 0.02-0.03 mg/kg diazepam, intravenously, increased 1 hr intake 54-75% above control levels. Intake was stimulated when the diet was a high grain, calorically dense one and also when the diet was a high fiber, calorically dilute one. Two young rapidly growing weanling horses showed an even more pronounced stimulation of intake. Following diazepam 1 hr intake was increased 105-240% above control lelvels. Promazine at a dose of 0.5 mg/kg also stimulated intake in adult horses, but not as markedly as did diazepam. A transquilizer and a neuroleptic appear to have a stimulatory eff upon short-term intake in horses.
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ISSN 0091-3057 ISBN Medium
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Notes (up) PMID:1005496 Approved no
Call Number refbase @ user @ Serial 60
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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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Notes (up) PMID:10080246 Approved no
Call Number Equine Behaviour @ team @ Serial 4064
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Author Gulotta, M.; Gilmanshin, R.; Buscher, T.C.; Callender, R.H.; Dyer, R.B.
Title Core formation in apomyoglobin: probing the upper reaches of the folding energy landscape Type Journal Article
Year 2001 Publication Biochemistry Abbreviated Journal Biochemistry
Volume 40 Issue 17 Pages 5137-5143
Keywords Animals; Apoproteins/*chemistry; Computer Simulation; Horses; Hydrogen-Ion Concentration; Kinetics; Models, Molecular; Myoglobin/*chemistry; *Protein Folding; Protein Structure, Secondary; Protein Structure, Tertiary; Spectrometry, Fluorescence/instrumentation/methods; Thermodynamics; Tryptophan/chemistry
Abstract An acid-destabilized form of apomyoglobin, the so-called E state, consists of a set of heterogeneous structures that are all characterized by a stable hydrophobic core composed of 30-40 residues at the intersection of the A, G, and H helices of the protein, with little other secondary structure and no other tertiary structure. Relaxation kinetics studies were carried out to characterize the dynamics of core melting and formation in this protein. The unfolding and/or refolding response is induced by a laser-induced temperature jump between the folded and unfolded forms of E, and structural changes are monitored using the infrared amide I' absorbance at 1648-1651 cm(-1) that reports on the formation of solvent-protected, native-like helix in the core and by fluorescence emission changes from apomyoglobin's Trp14, a measure of burial of the indole group of this residue. The fluorescence kinetics data are monoexponential with a relaxation time of 14 micros. However, infrared kinetics data are best fit to a biexponential function with relaxation times of 14 and 59 micros. These relaxation times are very fast, close to the limits placed on folding reactions by diffusion. The 14 micros relaxation time is weakly temperature dependent and thus represents a pathway that is energetically downhill. The appearance of this relaxation time in both the fluorescence and infrared measurements indicates that this folding event proceeds by a concomitant formation of compact secondary and tertiary structures. The 59 micros relaxation time is much more strongly temperature dependent and has no fluorescence counterpart, indicating an activated process with a large energy barrier wherein nonspecific hydrophobic interactions between helix A and the G and H helices cause some helix burial but Trp14 remains solvent exposed. These results are best fit by a multiple-pathway kinetic model when U collapses to form the various folded core structures of E. Thus, the results suggest very robust dynamics for core formation involving multiple folding pathways and provide significant insight into the primary processes of protein folding.
Address Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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ISSN 0006-2960 ISBN Medium
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Notes (up) PMID:11318635 Approved no
Call Number Equine Behaviour @ team @ Serial 3789
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Author Haruta, N.; Kitagawa, T.
Title Time-resolved UV resonance Raman investigation of protein folding using a rapid mixer: characterization of kinetic folding intermediates of apomyoglobin Type Journal Article
Year 2002 Publication Biochemistry Abbreviated Journal Biochemistry
Volume 41 Issue 21 Pages 6595-6604
Keywords Animals; Apoproteins/*chemistry; Circular Dichroism; Holoenzymes/chemistry; Horses; Hydrochloric Acid/chemistry; Hydrogen-Ion Concentration; Imidazoles/chemistry; Kinetics; Models, Molecular; Myoglobin/*chemistry; Peptide Fragments/chemistry; *Protein Folding; Protein Structure, Secondary; Spectrum Analysis, Raman/*methods; Tryptophan/*chemistry; Ultraviolet Rays; Whales
Abstract The 244-nm excited transient UV resonance Raman spectra are observed for the refolding intermediates of horse apomyoglobin (h-apoMb) with a newly constructed mixed flow cell system, and the results are interpreted on the basis of the spectra observed for the equilibrium acid unfolding of the same protein. The dead time of mixing, which was determined with the appearance of UV Raman bands of imidazolium upon mixing of imidazole with acid, was 150 micros under the flow rate that was adopted. The pH-jump experiments of h-apoMb from pH 2.2 to 5.6 conducted with this device demonstrated the presence of three folding intermediates. On the basis of the analysis of W3 and W7 bands of Trp7 and Trp14, the first intermediate, formed before 250 micros, involved incorporation of Trp14 into the alpha-helix from a random coil. The frequency shift of the W3 band of Trp14 observed for this process was reproduced with a model peptide of the A helix when it forms the alpha-helix. In the second intermediate, formed around 1 ms after the start of refolding, the surroundings of both Trp7 and Trp14 were significantly hydrophobic, suggesting the formation of the hydrophobic core. In the third intermediate appearing around 3 ms, the hydrophobicity was relaxed to the same level as that of the pH 4 equilibrium intermediate, which was investigated in detail with the stationary state technique. The change from the third intermediate to the native state needs more time than 40 ms, while the appearance of the native spectrum after the mixing of the same solutions was confirmed separately.
Address School of Mathematical and Physical Sciences, The Graduate University for Advanced Studies, Myodaiji, Okazaki 444-8585, Japan
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Notes (up) PMID:12022863 Approved no
Call Number Equine Behaviour @ team @ Serial 3785
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Author Piccione, G.; Caola, G.; Refinetti, R.
Title Temporal relationships of 21 physiological variables in horse and sheep Type Journal Article
Year 2005 Publication Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology Abbreviated Journal Comp Biochem Physiol A Mol Integr Physiol
Volume 142 Issue 4 Pages 389-396
Keywords Animals; Behavior, Animal/physiology; Blood Glucose/physiology; Body Temperature/*physiology; Circadian Rhythm/*physiology; Female; Horses/*physiology; Melatonin/blood/*physiology; Motor Activity/*physiology; Rectum/physiology; Sheep/*physiology; Time Factors
Abstract Daily or circadian oscillation has been documented in a variety of physiological and behavioral processes. Although individual variables have been studied in great detail, very few studies have been conducted on the temporal relationships between the rhythms of different variables. It is not known whether the circadian pacemaker generates each and every rhythm individually or whether most rhythms are simply derived from a few clock-controlled rhythms. As a first step in elucidating this issue, 21 physiological variables were recorded simultaneously in horse and sheep. The results indicated that, in both species, different variables exhibit different degrees of daily rhythmicity and reach their daily peaks at different times of the day. The variables exhibiting strongest rhythmicity were locomotor activity, rectal temperature, and plasma concentrations of melatonin and glucose. Comparison of rhythmicity and acrophase in the various rhythms allowed inferences to be made about mechanisms of causation.
Address Dipartimento di Morfologia, Biochimica, Fisiologia e Produzioni Animali, Facolta di Medicina Veterinaria, Universita degli Studi di Messina, 98168 Messina, Italy
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ISSN 1095-6433 ISBN Medium
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Notes (up) PMID:16290083 Approved no
Call Number Serial 1884
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