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Author |
Haruta, N.; Kitagawa, T. |
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Title |
Time-resolved UV resonance Raman investigation of protein folding using a rapid mixer: characterization of kinetic folding intermediates of apomyoglobin |
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Journal Article |
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Year |
2002 |
Publication |
Biochemistry |
Abbreviated Journal |
Biochemistry |
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Volume |
41 |
Issue |
21 |
Pages |
6595-6604 |
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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 |
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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. |
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School of Mathematical and Physical Sciences, The Graduate University for Advanced Studies, Myodaiji, Okazaki 444-8585, Japan |
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0006-2960 |
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PMID:12022863 |
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Equine Behaviour @ team @ |
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3785 |
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Author |
Dyer, F.C. |
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Title |
Animal behaviour: when it pays to waggle |
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Year |
2002 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
419 |
Issue |
6910 |
Pages |
885-886 |
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Keywords |
*Animal Communication; Animals; Bees/*physiology; California; Dancing/physiology; Environment; Evolution; Female; Flowers/chemistry; *Food; Gravitation; Lighting; Motor Activity/*physiology; Odors; Seasons; Sunlight |
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0028-0836 |
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PMID:12410290 |
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refbase @ user @ |
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769 |
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Author |
Nicol, C.J.; Davidson, H.P.D.; Harris, P.A.; Waters, A.J.; Wilson, A.D. |
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Title |
Study of crib-biting and gastric inflammation and ulceration in young horses |
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Journal Article |
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Year |
2002 |
Publication |
The Veterinary record |
Abbreviated Journal |
Vet. Rec. |
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Volume |
151 |
Issue |
22 |
Pages |
658-662 |
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Keywords |
Animal Husbandry/methods; Animals; Antacids/therapeutic use; *Behavior, Animal; Diet/veterinary; Endoscopy, Gastrointestinal/veterinary; Feces/chemistry; Female; Gastritis/diet therapy/physiopathology/*veterinary; Horse Diseases/diet therapy/*physiopathology/psychology; Horses; Hydrogen-Ion Concentration; Male; Random Allocation; Stereotyped Behavior/*physiology; Stomach Ulcer/diet therapy/physiopathology/*veterinary; Treatment Outcome; Weaning |
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Nineteen young horses that had recently started to perform the stereotypy of crib-biting were compared with 16 non-stereotypic horses for 14 weeks. After initial observations of their behaviour and an endoscopic examination of the condition of their stomachs, the horses were randomly allocated to a control or an antacid diet At the start of the trial, the stomachs of the crib-biting foals were significantly more ulcerated and inflamed than the stomachs of the normal foals. In addition, the faecal pH of the crib-biting foals (6.05) was significantly lower than that of the normal foals (6.58). The antacid diet resulted in a significant improvement in the condition of the horses' stomachs. The crib-biting behaviour declined in most of the foals, regardless of their diet, but tended to decline to a greater extent in the foals on the antacid diet. |
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Department of Clinical Veterinary Science, University of Bristol, Langford House, Bristol BS40 5DU |
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0042-4900 |
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PMID:12498408 |
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Call Number |
refbase @ user @ |
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83 |
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Author |
Touma, C.; Sachser, N.; Mostl, E.; Palme, R. |
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Title |
Effects of sex and time of day on metabolism and excretion of corticosterone in urine and feces of mice |
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Journal Article |
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Year |
2003 |
Publication |
General and Comparative Endocrinology |
Abbreviated Journal |
Gen Comp Endocrinol |
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Volume |
130 |
Issue |
3 |
Pages |
267-278 |
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Keywords |
Animals; Chromatography, High Pressure Liquid; Circadian Rhythm/*physiology; Corticosterone/*metabolism/urine; Feces/*chemistry; Female; Immunoenzyme Techniques; Kinetics; Male; Mice; Mice, Inbred C57BL; Reference Values; Sex Factors; Stress/metabolism; Time Factors; Tritium |
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Non-invasive techniques to monitor stress hormones in small animals like mice offer several advantages and are highly demanded in laboratory as well as in field research. Since knowledge about the species-specific metabolism and excretion of glucocorticoids is essential to develop such a technique, we conducted radiometabolism studies in mice (Mus musculus f. domesticus, strain C57BL/6J). Each mouse was injected intraperitoneally with 740 kBq of 3H-labelled corticosterone and all voided urine and fecal samples were collected for five days. In a first experiment 16 animals (eight of each sex) received the injection at 9 a.m., while eight mice (four of each sex) were injected at 9 p.m. in a second experiment. In both experiments radioactive metabolites were recovered predominantly in the feces, although males excreted significantly higher proportions via the feces (about 73%) than females (about 53%). Peak radioactivity in the urine was detected within about 2h after injection, while in the feces peak concentrations were observed later (depending on the time of injection: about 10h postinjection in experiment 1 and about 4h postinjection in experiment 2, thus proving an effect of the time of day). The number and relative abundance of fecal [3H]corticosterone metabolites was determined by high performance liquid chromatography (HPLC). The HPLC separations revealed that corticosterone was extensively metabolized mainly to more polar substances. Regarding the types of metabolites formed, significant differences were found between males and females, but not between the experiments. Additionally, the immunoreactivity of these metabolites was assessed by screening the HPLC fractions with four enzyme immunoassays (EIA). However, only a newly established EIA for 5alpha-pregnane-3beta,11beta,21-triol-20-one (measuring corticosterone metabolites with a 5alpha-3beta,11beta-diol structure) detected several peaks of radioactive metabolites with high intensity in both sexes, while the other EIAs showed only minor immunoreactivity. Thus, our study for the first time provides substantial information about metabolism and excretion of corticosterone in urine and feces of mice and is the first demonstrating a significant impact of the animals' sex and the time of day. Based on these data it should be possible to monitor adrenocortical activity non-invasively in this species by measuring fecal corticosterone metabolites with the newly developed EIA. Since mice are extensively used in research world-wide, this could open new perspectives in various fields from ecology to behavioral endocrinology. |
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Department of Behavioral Biology, Institute of Neuro and Behavioral Biology, University of Muenster, Badestrasse 9, D-48149 Muenster, Germany. touma@uni-muenster.de |
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0016-6480 |
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PMID:12606269 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
4086 |
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Author |
Gulotta, M.; Rogatsky, E.; Callender, R.H.; Dyer, R.B. |
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Title |
Primary folding dynamics of sperm whale apomyoglobin: core formation |
Type |
Journal Article |
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Year |
2003 |
Publication |
Biophysical Journal |
Abbreviated Journal |
Biophys J |
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Volume |
84 |
Issue |
3 |
Pages |
1909-1918 |
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Keywords |
Animals; Apoproteins/*chemistry; Crystallography/*methods; Horses; Myocardium/chemistry; Myoglobin/*chemistry; Protein Conformation; *Protein Folding; Species Specificity; Structure-Activity Relationship; Temperature; Whales |
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Abstract |
The structure, thermodynamics, and kinetics of heat-induced unfolding of sperm whale apomyoglobin core formation have been studied. The most rudimentary core is formed at pH(*) 3.0 and up to 60 mM NaCl. Steady state for ultraviolet circular dichroism and fluorescence melting studies indicate that the core in this acid-destabilized state consists of a heterogeneous composition of structures of approximately 26 residues, two-thirds of the number involved for horse heart apomyoglobin under these conditions. Fluorescence temperature-jump relaxation studies show that there is only one process involved in Trp burial. This occurs in 20 micro s for a 7 degrees jump to 52 degrees C, which is close to the limits placed by diffusion on folding reactions. However, infrared temperature jump studies monitoring native helix burial are biexponential with times of 5 micro s and 56 micro s for a similar temperature jump. Both fluorescence and infrared fast phases are energetically favorable but the slow infrared absorbance phase is highly temperature-dependent, indicating a substantial enthalpic barrier for this process. The kinetics are best understood by a multiple-pathway kinetics model. The rapid phases likely represent direct burial of one or both of the Trp residues and parts of the G- and H-helices. We attribute the slow phase to burial and subsequent rearrangement of a misformed core or to a collapse having a high energy barrier wherein both Trps are solvent-exposed. |
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Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA. gulotta@aecom.yu.edu |
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0006-3495 |
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PMID:12609893 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3783 |
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Author |
Carroll, J.; Murphy, C.J.; Neitz, M.; Hoeve, J.N.; Neitz, J. |
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Title |
Photopigment basis for dichromatic color vision in the horse |
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Journal Article |
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Year |
2001 |
Publication |
Journal of Vision |
Abbreviated Journal |
J Vis |
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Volume |
1 |
Issue |
2 |
Pages |
80-87 |
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Keywords |
Adaptation, Physiological; Animals; Color Perception/*physiology; Cones (Retina)/chemistry/*physiology; Electroretinography; Horses/*physiology; Photic Stimulation; Phototransduction/physiology; Retinal Pigments/analysis/*physiology; Visual Perception/physiology |
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Horses, like other ungulates, are active in the day, at dusk, dawn, and night; and, they have eyes designed to have both high sensitivity for vision in dim light and good visual acuity under higher light levels (Walls, 1942). Typically, daytime activity is associated with the presence of multiple cone classes and color-vision capacity (Jacobs, 1993). Previous studies in other ungulates, such as pigs, goats, cows, sheep and deer, have shown that they have two spectrally different cone types, and hence, at least the photopigment basis for dichromatic color vision (Neitz & Jacobs, 1989; Jacobs, Deegan II, Neitz, Murphy, Miller, & Marchinton, 1994; Jacobs, Deegan II, & Neitz, 1998). Here, electroretinogram flicker photometry was used to measure the spectral sensitivities of the cones in the domestic horse (Equus caballus). Two distinct spectral mechanisms were identified and are consistent with the presence of a short-wavelength-sensitive (S) and a middle-to-long-wavelength-sensitive (M/L) cone. The spectral sensitivity of the S cone was estimated to have a peak of 428 nm, while the M/L cone had a peak of 539 nm. These two cone types would provide the basis for dichromatic color vision consistent with recent results from behavioral testing of horses (Macuda & Timney, 1999; Macuda & Timney, 2000; Timney & Macuda, 2001). The spectral peak of the M/L cone photopigment measured here, in vivo, is similar to that obtained when the gene was sequenced, cloned, and expressed in vitro (Yokoyama & Radlwimmer, 1999). Of the ungulates that have been studied to date, all have the photopigment basis for dichromatic color vision; however, they differ considerably from one another in the spectral tuning of their cone pigments. These differences may represent adaptations to the different visual requirements of different species. |
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Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA |
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1534-7362 |
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PMID:12678603 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
4060 |
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Author |
Hoang, L.; Maity, H.; Krishna, M.M.G.; Lin, Y.; Englander, S.W. |
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Title |
Folding units govern the cytochrome c alkaline transition |
Type |
Journal Article |
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Year |
2003 |
Publication |
Journal of Molecular Biology |
Abbreviated Journal |
J Mol Biol |
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Volume |
331 |
Issue |
1 |
Pages |
37-43 |
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Keywords |
Animals; Cytochrome c Group/*chemistry; Horses; Hydrogen/chemistry; Hydrogen-Ion Concentration; Kinetics; Models, Molecular; *Protein Folding; Protein Structure, Tertiary; Spectrum Analysis; Titrimetry |
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Abstract |
The alkaline transition of cytochrome c is a model for protein structural switching in which the normal heme ligand is replaced by another group. Stopped flow data following a jump to high pH detect two slow kinetic phases, suggesting two rate-limiting structure changes. Results described here indicate that these events are controlled by the same structural unfolding reactions that account for the first two steps in the reversible unfolding pathway of cytochrome c. These and other results show that the cooperative folding-unfolding behavior of protein foldons can account for a variety of functional activities in addition to determining folding pathways. |
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Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6059, USA. lhoang@mail.upenn.edu |
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0022-2836 |
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PMID:12875834 |
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no |
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Equine Behaviour @ team @ |
Serial |
3781 |
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Author |
Miksovska, J.; Larsen, R.W. |
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Title |
Photothermal studies of pH induced unfolding of apomyoglobin |
Type |
Journal Article |
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Year |
2003 |
Publication |
Journal of Protein Chemistry |
Abbreviated Journal |
J Protein Chem |
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Volume |
22 |
Issue |
4 |
Pages |
387-394 |
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Keywords |
Acoustics; Animals; Apoproteins/*chemistry/metabolism; Circular Dichroism; Horses; Myocardium/chemistry; Myoglobin/*chemistry/metabolism; Photolysis; Protein Conformation/radiation effects; Protein Denaturation/radiation effects; *Protein Folding; Temperature; Thermodynamics |
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Conformational dynamic and enthalpy changes associated with pH induced unfolding of apomyoglobin were studied using photoacoustic calorimetry and photothermal beam deflection methods. The transition between the native state and the I intermediate was induced by a nanosecond pH jump from o-nitrobenzaldehyde photolysis. Deconvolution of photoacoustic waves indicates two kinetic processes. The fast phase (T < 50 ns) is characterized by a volume expansion of 8.8 ml mol(-1). This process is followed by a volume contraction of about -22 ml mol(-1) (tau approximately 500 ns). Photothermal beam deflection measurements do not reveal any volume changes on the time scale between approximately 100 micros and 5 ms. We associate the volume contraction with structural changes occurring during the transition between the native state and the I intermediate. The lack of any processes on the ms time scale may indicate the absence of structural events involving larger conformational changes of apomyoglobin after the pH jump. |
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Department of Chemistry, University of South Florida, Tampa, Florida 33620, USA |
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0277-8033 |
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PMID:13678303 |
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no |
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Equine Behaviour @ team @ |
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3780 |
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Author |
Ganswindt, A.; Palme, R.; Heistermann, M.; Borragan, S.; Hodges, J.K. |
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Title |
Non-invasive assessment of adrenocortical function in the male African elephant (Loxodonta africana) and its relation to musth |
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Journal Article |
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Year |
2003 |
Publication |
General and Comparative Endocrinology |
Abbreviated Journal |
Gen Comp Endocrinol |
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Volume |
134 |
Issue |
2 |
Pages |
156-166 |
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Keywords |
Adrenal Cortex/*metabolism/secretion; Adrenal Cortex Function Tests/methods/*veterinary; Adrenocorticotropic Hormone/physiology; Animals; Carbon Isotopes/diagnostic use; Chromatography, High Pressure Liquid/veterinary; Elephants/*metabolism/urine; Feces/*chemistry; Glucocorticoids/analysis/urine; Hydrocortisone/*analysis/diagnostic use/urine; Immunoenzyme Techniques/methods/veterinary; Male; Reproduction/physiology; Sexual Behavior, Animal/physiology; Stress, Psychological/diagnosis/*physiopathology; Testosterone/*analysis/diagnostic use/urine |
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Adult male elephants periodically show the phenomenon of musth, a condition associated with increased aggressiveness, restlessness, significant weight reduction and markedly elevated androgen levels. It has been suggested that musth-related behaviours are costly and that therefore musth may represent a form of physiological stress. In order to provide data on this largely unanswered question, the first aim of this study was to evaluate different assays for non-invasive assessment of adrenocortical function in the male African elephant by (i) characterizing the metabolism and excretion of [3H]cortisol (3H-C) and [14C]testosterone (14C-T) and (ii) using this information to evaluate the specificity of four antibodies for determination of excreted cortisol metabolites, particularly with respect to possible cross-reactions with androgen metabolites, and to assess their biological validity using an ACTH challenge test. Based on the methodology established, the second objective was to provide data on fecal cortisol metabolite concentrations in bulls during the musth and non-musth condition. 3H-C (1 mCi) and 14C-T (100 microCi) were injected simultaneously into a 16 year old male and all urine and feces collected for 30 and 86 h, respectively. The majority (82%) of cortisol metabolites was excreted into the urine, whereas testosterone metabolites were mainly (57%) excreted into the feces. Almost all radioactive metabolites recovered from urine were conjugated (86% 3H-C and 97% 14C-T). In contrast, 86% and >99% of the 3H-C and 14C-T metabolites recovered from feces consisted of unconjugated forms. HPLC separations indicated the presence of various metabolites of cortisol in both urine and feces, with cortisol being abundant in hydrolysed urine, but virtually absent in feces. Although all antibodies measured substantial amounts of immunoreactivity after HPLC separation of peak radioactive samples and detected an increase in glucocorticoid output following the ACTH challenge, only two (in feces against 3alpha,11-oxo-cortisol metabolites, measured by an 11-oxo-etiocholanolone-EIA and in urine against cortisol, measured by a cortisol-EIA) did not show substantial cross-reactivity with excreted 14C-T metabolites and could provide an acceptable degree of specificity for reliable assessment of glucocorticoid output from urine and feces. Based on these findings, concentrations of immunoreactive 3alpha,11-oxo-cortisol metabolites were determined in weekly fecal samples collected from four adult bulls over periods of 11-20 months to examine whether musth is associated with increased adrenal activity. Results showed that in each male levels of these cortisol metabolites were not elevated during periods of musth, suggesting that in the African elephant musth is generally not associated with marked elevations in glucocorticoid output. Given the complex nature of musth and the variety of factors that are likely to influence its manifestation, it is clear, however, that further studies, particularly on free-ranging animals, are needed before a possible relationship between musth and adrenal function can be resolved. This study also clearly illustrates the potential problems associated with cross-reacting metabolites of gonadal steroids in EIAs measuring glucocorticoid metabolites. This has to be taken into account when selecting assays and interpreting results of glucocorticoid metabolite analysis, not only for studies in the elephant but also in other species. |
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German Primate Centre, Department of Reproductive Biology, Kellnerweg 4, 37077 Gottingen, Germany. ganswindt@www.dpz.gdwg.de |
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0016-6480 |
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PMID:14511986 |
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Equine Behaviour @ team @ |
Serial |
4085 |
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Author |
Uzawa, T.; Akiyama, S.; Kimura, T.; Takahashi, S.; Ishimori, K.; Morishima, I.; Fujisawa, T. |
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Title |
Collapse and search dynamics of apomyoglobin folding revealed by submillisecond observations of alpha-helical content and compactness |
Type |
Journal Article |
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Year |
2004 |
Publication |
Proceedings of the National Academy of Sciences of the United States of America |
Abbreviated Journal |
Proc. Natl. Acad. Sci. U.S.A. |
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Volume |
101 |
Issue |
5 |
Pages |
1171-1176 |
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Keywords |
Animals; Apoproteins/*chemistry; Circular Dichroism; Cytochromes c/chemistry; Horses; Myoglobin/*chemistry; *Protein Folding; *Protein Structure, Secondary; Scattering, Radiation |
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Abstract |
The characterization of protein folding dynamics in terms of secondary and tertiary structures is important in elucidating the features of intraprotein interactions that lead to specific folded structures. Apomyoglobin (apoMb), possessing seven helices termed A-E, G, and H in the native state, has a folding intermediate composed of the A, G, and H helices, whose formation in the submillisecond time domain has not been clearly characterized. In this study, we used a rapid-mixing device combined with circular dichroism and small-angle x-ray scattering to observe the submillisecond folding dynamics of apoMb in terms of helical content (f(H)) and radius of gyration (R(g)), respectively. The folding of apoMb from the acid-unfolded state at pH 2.2 was initiated by a pH jump to 6.0. A significant collapse, corresponding to approximately 50% of the overall change in R(g) from the unfolded to native conformation, was observed within 300 micros after the pH jump. The collapsed intermediate has a f(H) of 33% and a globular shape that involves >80% of all its atoms. Subsequently, a stepwise helix formation was detected, which was interpreted to be associated with a conformational search for the correct tertiary contacts. The characterized folding dynamics of apoMb indicates the importance of the initial collapse event, which is suggested to facilitate the subsequent conformational search and the helix formation leading to the native structure. |
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Address |
Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo, Kyoto 615-8510, Japan |
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Publisher |
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Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0027-8424 |
ISBN |
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Conference |
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Notes |
PMID:14711991 |
Approved |
no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3779 |
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