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PubMed1987

Assignment of hyperfine shifted haem methyl carbon resonances in paramagnetic low-spin met-cyano complex of sperm whale myoglobin.

The hyperfine shifted resonances arising from all four individual haem carbons of the paramagnetic low-spin met-cyano complex of sperm whale myoglobin have been clearly identified and assigned for the first time with the aid of 1H-13C heteronuclear chemical shift correlated spectroscopy. Alteration of the in-plane symmetry of the electronic structure of haem induced by the ligation of proximal histidyl imidazole spreads the haem carbon resonances to 32 ppm at 22 degrees C, indicating the sensitivity of those resonances to the haem electronic/molecular structure. Those resonances are potentially powerful probes in characterizing the nature of haem electronic structure.

Animals↗

PubMed1993

Crystal structure of a distal site double mutant of sperm whale myoglobin at 1.6 A resolution.

The three-dimensional structure of sperm whale myoglobin His64(E7)-->Val,Thr67(E10)-->Arg double mutant has been studied by X-ray crystallography at 1.6 A resolution, and refined to a crystallographic R-factor of 0.197. The Arg67(E10) side chain is extended in the direction of the ligand binding site, and its NH1 atom is at a distance of 3.11 A from the NH1 atom of Arg45(CD3), which is also pointing towards the distal site. Both are kept in this position by hydrogen bonding and electrostatic interactions with a solvent sulfate ion, located amongst the two, on the protein surface. No liganded water molecule is present at the sixth coordination position of the Fe(III) heme.

Animals↗

PubMed1994

Engineering Ascaris hemoglobin oxygen affinity in sperm whale myoglobin: role of tyrosine B10.

The contribution to oxygen stabilization of a tyrosine residue in topological position (B10) has been studied in sperm whale myoglobin by simultaneous replacement of residues at positions (B10), (E7) and (E10) as suggested by analysis of the sequence of high oxygen affinity hemoglobins, such as that of the nematode Ascaris suum. Kinetic and equilibrium experiments with the gaseous ligands oxygen and carbon monoxide show that indeed the introduction of tyrosine (B10), together with replacement of the distal histidine (E7) with glutamine, is associated with a large decrease in the oxygen dissociation rate constant. Our results are consistent with the possible formation in the distal pocket of two hydrogen bonds with the iron-bound oxygen.

Amino Acid Sequence↗

PubMed1987

Assignment of resonances in the 1H nuclear magnetic resonance spectrum of the carbon monoxide complex of sperm whale myoglobin by phase-sensitive two-dimensional techniques.

Phase-sensitive two-dimensional nuclear magnetic resonance (n.m.r.) experiments have been used to obtain extensive proton resonance assignments for the carbon monoxide complex of sperm whale myoglobin. Multiple quantum experiments were particularly important in the assignment procedure. The assignments are the most complete yet reported for a protein of such high molecular weight (approximately 18,000) and make possible new and comprehensive studies of the structure and dynamics of carbonmonoxymyoglobin in solution. Assignments for seven of the histidine residues are reported, including the critical proximal and distal histidines. Most of these are at variance with the assignments already in the literature. The present n.m.r. data indicate that histidines 24 (B5) and 119 (GH1) are hydrogen bonded to each other and, in contrast to neutron diffraction data, show that His24 does not protonate at pH greater than 5. The aromatic rings of all the phenylalanine and tyrosine residues undergo rapid flips about the ring axis. The side-chains of Leu89 (F4) and Phe138 (H15), which border a large hydrophobic cavity, are particularly mobile.

Amino Acid Sequence↗

PubMed1991

X-ray crystal structure of the ferric sperm whale myoglobin: imidazole complex at 2.0 A resolution.

The X-ray crystal structure of the ferric sperm whale (Physeter catodon) myoglobin:imidazole complex has been refined at 2.0 A resolution, to a final R-factor of 14.8%. The overall conformation of the protein is little affected by binding of the ligand. Imidazole is co-ordinated to the heme iron at the distal site, and forces distinguishable local changes in the surrounding protein residues. His64(E7) swings out of the distal pocket and becomes substantially exposed to the solvent: nevertheless, it stabilizes the exogenous ligand by hydrogen bonding. The side-chains of residues Arg45(CD3) and Asp60(E3) are also affected by imidazole association.

Animals↗

PubMed1996

Mercury in pilot whales: possible limits to the detoxification process.

The ability of pilot whales (Globicephala melas) to concentrate cadmium and mercury is well established. The levels of these metals were generally higher than those encountered in other species of marine mammals. The biological data have not revealed a major toxic problem in the population, and this suggests a remarkable tolerance of this species to heavy metals. Cellular distribution of mercury was carried out in liver samples. The presence of metallothionein-like proteins in the soluble fraction has been demonstrated, but 95% of mercury was mainly bound to the insoluble fraction, showing that these proteins had no role in this metal detoxification. The molar ratio between mercury and selenium suggests that the major mechanism of detoxification is through the formation of a complex Hg-Se which leads to the demethylation of mercury. The site of this process is the liver in which mercury mainly appeared as inorganic, whereas in the muscle the percentage of organic to total mercury was much higher. Nevertheless, this detoxification is limited in lactating females and in all the individuals of one school. This could be the result of changes in the diet and could constitute a toxicological risk for the species.

Animal Nutritional Physiological Phenomena↗

PubMed1996

Hepatocyte vacuolation and autolytic changes in the liver of pilot whales, Globicephala melas, stranded on Cape Cod, MA, USA.

Most cetacea available for internal sampling in recent times have died through mass or single stranding events. It is important to know how the time elapsed between death and sampling affect quality of tissues. This study evaluated histological quality in the liver of long-finned pilot whales that either died or were euthanased after mass stranding events. Histological detection of significant autolysis was found in animals when 2 or more hours elapsed between death and sampling. In addition, hepatocytes often had marked idiopathic cytoplasmic vacuolation that did not stain with hematoxylin and eosin. The extent of this vacuolation did not show any correlation with time between death and sampling, but did appear more often in animals of greater total length. These observations suggest that when animals die or are euthanased at a single or mass stranding, every effort should be made to obtain samples as soon as possible, although meaningful histological observations can still be made in the presence of significant autolysis. These data also suggest that a multi-disciplinary study should be conducted to determine whether increasing autolysis is associated with changes in the organic chemical residues, molecular biology, histopathology and microbiology of those tissues.

Animals↗

PubMed1987

Natural antibodies to human lymphocytes and erythrocytes in the serum of Orcinus orca killer whale.

The existence of naturally occurring heterophile antibodies to antigenic determinants on human blood cell membranes has long been known. It has been shown that the serum of Orcinus orca (Killer whale) does contain similar antibody. Absorption techniques in concert with either microagglutination or complement-dependent microcytotoxicity assays revealed at least three antibody specificities erythrocyte (RBC), B-lymphocyte and T-lymphocyte. Human erythrocyte specificity has been separated from other mammalian RBC specificity, and higher microagglutination titers and/or scores were observed with human group A RBC's than with group B,O, or AB. Tests run at 4 degrees, 20 degrees and 37 degrees C). Higher microcytotoxicity and microagglutination activity was demonstrated with B versus T lymphocytes. It is hoped that the characterization of the antigenic specificity of these heterophile agglutinins will prove to be useful as a biological reagent-tool which may be applied to the identification of a new receptor on human lymphocytes and/or erythrocytes. Also, if isolated, these agglutinins could be useful in the study of the occurrence and presence of specific receptors on cell membranes and give insight as to how these receptors change in health, disease and malignancy.

Agglutinins↗

PubMed1982

Production of monoclonal antibodies with pre-selected submolecular binding specificities to protein determinants: demonstration with sperm whale myoglobin.

Two monoclonal antibodies with pre-selected submolecular binding specificities to sperm whale myoglobin (Mb) were obtained by hybridizing Fa/0 mouse myeloma cells with spleen cells derived from mice which had been immunized with free (not coupled to any carrier) Mb synthetic peptides 132-153 or 145-151 (antigenic site 5). Both monoclonal antibodies were IgG1 (k). Their homogeneity was confirmed by analytical isoelectric focusing electrophoresis. According to competitive inhibition studies in which Mb, the five synthetic antigenic sites of Mb, Mb peptide 132-153, bovine serum albumin (BSA), and lysozyme were used as inhibitors, the binding specificities of both monoclonal antibodies were restricted to determinants present in the peptides used for immunizations. The results of direct binding studies confirmed this conclusion and suggested that monoclonal antibodies with pre-selected submolecular binding specificities can be readily obtained by the techniques of somatic cell hybridization when the corresponding free synthetic determinants are used as immunogens.

Animals↗

PubMed1983

Production of monoclonal antibodies with preselected submolecular binding specificities to protein antigenic sites: antibodies to sperm whale myoglobin sites.

The five synthetic antigenic sites of sperm whale myoglobin were used in their free form (i.e. not coupled to any carrier) to immunize separate groups of BALB/cByJ mice. The synthetic peptides corresponded to: site 1, residues 15-22; site 2, residues 56-62; site 3, residues 94-99; site 4, residues 113-119; site 5, residues 145-151. Serum samples obtained from each group of mice contained antibodies that bound specifically to myoglobin and exclusively to the immunizing antigenic site. Monoclonal antibodies to each of the five antigenic sites were subsequently obtained by hybridizing Fa/O mouse myeloma cells with spleen cells derived from each group of mice. These monoclonal antibodies were either IgM(kappa) or IgGl(kappa). They expressed the same isotypes as the antigen specific serum antibodies produced by the mice whose spleen cells were used for hybridization. Solid phase radioimmunoassay studies also indicated that each monoclonal antibody, like the immune serum of the parent animals, bound specifically to myoglobin and exclusively to the synthetic peptide used as an immunogen. These results suggested that the hybridoma antibodies expressed submolecular binding specificities that were the result of peptide immunization rather than hybrid selection. This strongly supports our previous findings that it is possible to produce monoclonal antibodies with preselected submolecular binding specificities to continuous protein determinants by the techniques of somatic cell hybridization when the corresponding free synthetic determinants are used as immunogens.

Animals↗

PubMed1985

Assignment of heme and distal amino acid resonances in the 1H-NMR spectra of the carbon monoxide and oxygen complexes of sperm whale myoglobin.

Assignments of resonances of the heme and distal amino acid protons in spectra of the CO and O2 complexes of sperm whale myoglobin are reported. These resonances provide information on the conformation of the heme pocket. For oxymyoglobin, the assignments of the heme meso protons disagree with those proposed previously on the basis of partial deuteration experiments. Rapid ring flips about the C beta-C gamma bond are detected for Phe-CD1. Recent claims for two conformational substates of valine-E11 in carbonmonoxymyoglobin (Bradbury, J.H. and Carver, J.A. (1984) Biochemistry 23, 4905-4913) are shown to be in error. The pK of His-97 (FG3) in carbonmonoxymyoglobin has been determined (pK = 5.9). This residue appears to influence many spectroscopic properties of myoglobin. The distal His-E7 in carbonmonoxymyoglobin has pK less than 5.0. Differences in the heme pocket conformation in the CO complexes of myoglobin and leghemoglobin are discussed. These differences may be influential in O2 and CO association reactions.

Amino Acids↗

PubMed1988

pH-dependence of photo-induced electron transfer in zinc-substituted sperm whale myoglobin.

The electron transfer between the excited triplet state of zinc-substituted sperm whale myoglobin and Cu2+ has been studied by following the decay rate of delayed fluorescence. The Cu2+ bound on the surface of the myoglobin molecule are efficient quenchers of the excited electron state of Zn-myoglobin. Two bimolecular rate constants of quenching (KQ) for every pH investigated have been calculated. The pH-dependence of KQ1 indicates that the protonation of one amino acid residue (His-GH1 (119] is important for the process. Our results support the idea of the common nature of the mechanism of quenching by Cu2+ and oxidation of oxymyoglobin by Cu2+.

Animals↗

PubMed1990

1H-NMR study of the mechanism of assembly and equilibrium heme orientation of sperm whale myoglobin reconstituted with protohemin type-isomers.

The products of the incorporation of various protohemin type-isomers into the heme pocket of sperm whale myoglobin were investigated by 1H-NMR in the met-cyano complexes, both immediately after reconstitution as well as at equilibrium. The type-isomers studied include those involving all possible interchanges of the two substituents on a given pyrrole. The protohemin-III and -XIII isomers, with true 2-fold symmetry, yielded only homogeneous products. Protohemins-XI, -XIV both exhibited two species after reconstitution, with one disappearing with time. Protohemin-I was the only asymmetric hemin that failed to exhibit two isomers initially. The orientation of the hemin within the pocket was established by nuclear Overhauser detected dipolar connectivities among heme substituents and between heme substituents and assigned heme pocket residues. At equilibrium, the heme orientations were dominated by the asymmetric propionate rather than vinyl dispositions on the hemin, with a clear preference for placing a propionate at the 8- vs. 5-methyl position of native myoglobin. For protohemin-XI, the propionates were found in the unexpected positions of the 7-propionate and 2-vinyl groups of native myoglobin, indicating that propionates can occupy positions well within the hydrophobic interior. The alternate heme orientation for the metastable intermediates detected for protohemin-XI and -XIV involved rotational isomerism about the alpha,gamma-meso axes bisecting the vinyl positions, but these two axes are at right angles to each other in the protein matrix. The fact that protohemin-XIV, but not protohemin-I, exhibits a reversed orientation as a reconstitution intermediate provides direct evidence that vinyl contacts, as well as propionate links, modulate the relative stabilities of the initial encounter complexes between hemin and apomyoglobin. The heme cavity molecular/electronic structure was found largely unperturbed for the complexes of the various protohemin type-isomers.

Animals↗

PubMed1996

Heme geometry in the 10 K photoproduct from sperm whale carbonmonoxymyoglobin.

We have measured the Soret band of the photoproduct obtained by complete photolysis of sperm whale carbonmonoxymyoglobin at 10 K. The experimental spectrum has been modeled with an analytical expression that takes into account the homogeneous bandwidth, the coupling of the electronic transition with both high and low frequency vibrational modes, and the effects of static conformational heterogeneity. The comparison with deoxymyoglobin at low temperature reveals three main differences. In the photoproduct, the Soret band is shifted to red. The band is less asymmetric, and an enhanced coupling to the heme vibrational mode at 674 cm-1 is observed. These differences reflect incomplete relaxation of the active site after ligand dissociation. The smaller band asymmetry of the photoproduct can be explained by a smaller displacement of the iron atom from the mean porphyrin plane, in quantitative agreement with the X-ray structure analysis. The enhanced vibrational coupling is attributed to a subtle heme distortion from the planar geometry that is barely detectable in the X-ray structure.

Animals↗

PubMed1989

Arctic life adaptation--III. The function of whale (Balaenoptera acutorostrata) hemoglobin.

1. The oxygen binding properties of the hemoglobin from the Lesser Rorqual, Balaenoptera acutorostrata, has been investigated with respect to the possible effects of organic phosphates on gas transport in arctic environments. 2. The intrinsic oxygen affinity of the hemoglobin is high and strongly modulated by the effects of organic phosphates. 3. In the absence of organic phosphates, the temperature sensitivity of oxygen binding expressed by the heat of oxygenation, delta H, is -16.2 kcal/mol when corrected for the heat of oxygen in solution. 4. In the presence of organic phosphates there is a marked decrease in the temperature sensitivity delta H approximately -5 kcal/mol). 5. This feature is of great importance for oxygen unloading in the flippers and the tail, where the temperature is lower than the trunk of the whale. 6. Furthermore the organic phosphates strongly increase the Bohr coefficient, delta log P50/delta pH, from less than -0.3 in stripped hemoglobin to about -1.5 when the hemoglobin is saturated with P6-inositol. 7. This feature may be of great physiological importance by reducing the CO2 tension and acidosis after a prolonged dive.

Adaptation, Physiological↗

PubMedDate not supplied

Whale strandings: hypothesis.

The hypothesis is presented that whales become stranded inadvertently as a consequence of seeking stimulation. The animals enter shallow water in order to roll over, bask, and rub themselves in the sand, and are trapped by the receding tide. It suggested that stimulation-seeking behavior (and stranding) reflects a general sympathetic nervous system response which may be due to a number of factors such as pain, discomfort, reproductive state, and other biorhythmic changes.

Animals↗

PubMed1990

Ultrastructure of synapses and golgi analysis of neurons in neocortex of the lateral gyrus (visual cortex) of the dolphin and pilot whale.

Qualitative and computerized quantitative analyses of ultrastructural features of synapses in different layers of the primary visual cortex in the dolphin (Stenella coeruleoalba) and the pilot whale (Globicephala melaena) were carried out. Also, Golgi and cytoarchitectonic analyses were performed in the same species of cetaceans and, additionally, in Tursiops truncatus and Phocaena phocaena. It was found that on a synaptic level, as well as in cytoarchitectonic and Golgi features, the neocortex of cetaceans combines evolutionary progressive features and conservative features with a marked prevalence of the latter. Thus, the total number of synapses in visual neocortex in cetaceans is closer to this value in higher Primates. On the other hand, the laminar density of synapses per mm3 is generally the same in all layers in cetacean visual cortex and numerically is close to values found in small lissencephalic brains. Also, the synapse/neuron ratio in the dolphin visual cortex is of the same order as in cortices of rodents and lagomorphs and much higher than in cortices of advanced terrestrial mammals. Layers I and II contain approximately 70% of the total synapses in the cortical slab through visual cortex. Layer I also contains the extraverted dendrites of neurons of layer II and thus these two layers resemble a paleoarchicortical type of organization superimposed on a more typical neocortical organization of the lower cortical layers. In this respect the convexity neocortex of cetaceans is generally similar to the neocortices of phylogenetically ancient extant mammals such as basal Insectivora and Chiroptera.

Animals↗

PubMed2004

Characterization and profiling of hepatic cytochromes P450 and phase II xenobiotic-metabolizing enzymes in beluga whales (Delphinapterus leucas) from the St. Lawrence River Estuary and the Canadian Arctic.

Cytochromes P450 (CYP, phase I) and conjugating (phase II) enzymes can be induced by and influence the toxicokinetics (metabolism) and toxicity of xenobiotic contaminants in exposed organisms. Beluga whale (Delphinapterus leucas) from the endangered St. Lawrence (SL) River Estuary population exhibit deleterious health effects and various severe pathologies that have been associated with contaminant exposure. In contrast, such effects (e.g. reproductive and immunological impairment) are generally less frequent in less exposed populations in the Canadian Arctic (CA). In the present study, opportunistic sampling resulted in the collection immediately after death of liver tissue from a single female neonate SL beluga (SL6) and male and female CA beluga (n=10) from the Arviat region of western Hudson Bay, in addition to sampling of stranded carcasses of male and female SL beluga (n=5) at least 12 h postmortem. We immunologically characterized cross-reactive proteins of hepatic microsomal CYP1A, CYP2B, CYP3A, CYP2E, epoxide hydrolase (EH) and uridine diphosphoglucuronosyl transferase (UDPGT) isozymes. Cross-reactive proteins were found in all SL and CA beluga using anti-rat CYP1A1, anti-rainbow trout CYP3A, anti-human CYP2E1, anti-rabbit EH and anti-human UDPGT1A1 polyclonal antibodies (Abs), whereas faintly cross-reactive CYP2B proteins were only found in SL6 and the CA samples using an anti-rabbit CYP2B1 Ab. In corresponding catalytic activity assessments, only SL6 and all CA beluga microsomal samples exhibited CYP1A-mediated 7-ethoxyresorufin O-deethylase (EROD) activity (51-260 pmol/mg/min), CYP3A-mediated activity (113-899 pmol/mg/min) based on the formation of 6beta-hydroxytestosterone using a testosterone hydroxylase assay, and UDPGT activity (830-4956 pmol/mg/min) based on 1-naphthylglucuronide formation. The marginal cross-reactivity with the anti-CYP2B1 Ab and lack of catalytically measurable hydroxytestosterone isomers associated with CYP2B-type activity in all the SL and CA animals is suggestive of low CYP2B-type enzyme expression in beluga. The absence of measurable total P450 enzyme levels and catalytic activities in samples from the stranded SL belugas suggested catalytically inactive enzymes as a consequence of tissue degradation related due to the time delay of sample collection after death. However, all SL and CA animals demonstrated similar, immunologically cross-reactive phase I and II hepatic enzyme profiles, which is suggestive of the importance of metabolism in the toxicokinetics and fate of xenobiotics in animals from both populations

Animals↗