Haemocyanin function in the New Zealand abalones Haliotis iris and H. australis: relationships between oxygen-binding properties, muscle metabolism and habitat

1998 ◽  
Vol 49 (2) ◽  
pp. 143 ◽  
Author(s):  
Rufus M. G. Wells ◽  
John Baldwin ◽  
Scott R. Speed ◽  
Roy E. Weber
Keyword(s):  
Primary Source ◽  
Oxygen Storage ◽  
Oxygen Binding ◽  
Binding Properties ◽  
Muscle Enzyme ◽  
Atp Production ◽  
Muscle Work ◽  
Habitat Differences ◽  
Oxygen Stores ◽  
O2 Binding

Abalone have a well developed capacity for anaerobic metabolism in the pedal musculature, and during exercise the haemolymph oxygen stores may be reserved for more oxygen-dependent tissues. This implies that the haemocyanin-based oxygen transport system is poised towards oxygen storage rather than high rates of oxygen delivery. This proposition was examined by determining O2 -binding properties of haemocyanin from two species of abalone that differ in behaviour and environmental oxygen requirements. Both species showed reversed Bohr and Root effects leading to very high oxygen affinity and reduced cooperativity at low pH. A marked temperature sensitivity of haemocyanin–O2 binding in H. iris (with heat of oxygenation at –55.7 kJ mol-1) impairs oxygen loading above 20˚C and may explain the reduced size and density of populations in warmer northern waters. Muscle enzyme activities indicate low maximum rates of ATP production, with arginine phosphate hydrolysis as the primary source of ATP for elevated levels of muscle work. These data support the hypothesis that oxygen stores support high levels of aerobic muscle work. However, the similarities in enzyme profiles and haemocyanin properties could not be related to behavioural and habitat differences.

Haemoglobin-Oxygen Binding Properties in the Blood of Xenopus Laevis, with Special Reference to the Influences of Aestivation and of Temperature and Salinity Acclimation

1980 ◽  
Vol 86 (1) ◽  
pp. 19-37
Author(s):  
ALFRED JOKUMSEN ◽  
ROY E. WEBER
Keyword(s):  
Xenopus Laevis ◽  
Salt Water ◽  
Oxygen Affinity ◽  
Minor Component ◽  
Blood Levels ◽  
Oxygen Binding ◽  
Binding Properties ◽  
Salinity Acclimation ◽  
High O2 ◽  
O2 Binding

The oxygen equilibrium properties of blood and of solutions of haemoglobin from Xenopus laevis are reported. At pH 7.6 the oxygen affinity of the blood, expressed as half saturation oxygen tension (P50) amounts to 27.0 mm and 13.7 mmHg (3.60 and 1.83 kPa) when measured at 25 and 10 °C, while the Bohr factor (Δlog P50/ΔpH) was −0.40, and the Hill's cooperativity coefficient, n, averaged 2.1. These data reflect an overall heat of oxygenation, ΔH, of −7.9 kcal. mol−1, which decreased to −6.3 kcal. mol−1 when the live animals were acclimated to each measuring temperature. Xenopus blood showed a high O2 capacity (15 vol.%) compared to that of other amphibians. Acclimation to water of increased salinity (12%0), and aestivation, raised blood O2 affinity; at 25 °C and pH 7.6, P50 decreased to 21.1 and 25.2 mmHg (2.81 and 3.36 kPa), respectively. These changes were concomitant with increases in the blood levels of urea. In contrast to NaCl and ATP, urea increased O2 affinity of the purified haemoglobin, suggesting that oxygenationlinked binding to haemoglobin is involved in the modulations of the blood O2 affinity during aestivation and acclimation to salt water. Xenopus haemoglobin consists of two components. The major component is electrophoretically anodal, and has O2 binding properties similar to those of the haemolysate; the minor component is cathodal, and shows extremely low P50, pH sensitivity and cooperativity.

The archaeogastropod mollusc Haliotis iris: tissue and blood metabolites and allosteric regulation of haemocyanin function

2002 ◽  
Vol 205 (2) ◽  
pp. 253-263
Author(s):  
Jane W. Behrens ◽  
John P. Elias ◽  
H. Harry Taylor ◽  
Roy E. Weber
Keyword(s):  
Equilibrium Constants ◽  
Adductor Muscle ◽  
Interactive Effects ◽  
Oxygen Binding ◽  
Binding Properties ◽  
Adductor Muscles ◽  
Short Term Exposure ◽  
O2 Delivery ◽  
O2 Binding

SUMMARY We investigated divalent cation and anaerobic end-product concentrations and the interactive effects of these substances and pH on haemocyanin oxygen-binding (Hc-O2) in the New Zealand abalone Haliotis iris. During 24 h of environmental hypoxia (emersion), d-lactate and tauropine accumulated in the foot and shell adductor muscles and in the haemolymph of the aorta, the pedal sinus and adductor muscle lacunae, whereas l-lactate was not detected. Intramuscular and haemolymph d-lactate concentrations were similar, but tauropine accumulated to much higher levels in muscle tissues. Repeated disturbance and short-term exposure to air over 3 h induced no accumulation of d- or l-lactate and no change in [Ca2+], [Mg2+], pH and O2-binding properties of the native haemolymph. The haemolymph showed a low Hc-O2 affinity, a large reverse Bohr effect and marked cooperativity. Dialysis increased Hc-O2 affinity, obliterated cooperativity and decreased the pH-sensitivity of O2 binding. Replacing Mg2+ and Ca2+ restored the native O2-binding properties and the reverse Bohr shift. l- and d-lactate exerted minor modulatory effects on O2-affinity. At in vivo concentrations of Mg2+ and Ca2+, the cooperativity is dependent largely on Mg2+, which modulates the O2 association equilibrium constants of both the high-affinity (KR) and the low-affinity (KT) states (increasing and decreasing, respectively). This allosteric mechanism contrasts with that encountered in other haemocyanins and haemoglobins. The functional properties of H. iris haemocyanin suggest that high rates of O2 delivery to the tissues are not a priority but are consistent with the provision of a large O2 reserve for facultatively anaerobic tissues during internal hypoxia associated with clamping to the substratum.

scholarly journals Haemoglobin polymorphisms affect the oxygen-binding properties in Atlantic cod populations

2008 ◽  
Vol 276 (1658) ◽  
pp. 833-841 ◽  
Author(s):  
Øivind Andersen ◽  
Ola Frang Wetten ◽  
Maria Cristina De Rosa ◽  
Carl Andre ◽  
Cristiana Carelli Alinovi ◽  
...  
Keyword(s):  
Evolutionary Biology ◽  
Quaternary Structure ◽  
Atlantic Cod ◽  
Three Dimensional ◽  
Oxygen Affinity ◽  
Oxygen Binding ◽  
Low Oxygen ◽  
Binding Properties ◽  
Important Species ◽  
The North

A major challenge in evolutionary biology is to identify the genes underlying adaptation. The oxygen-transporting haemoglobins directly link external conditions with metabolic needs and therefore represent a unique system for studying environmental effects on molecular evolution. We have discovered two haemoglobin polymorphisms in Atlantic cod populations inhabiting varying temperature and oxygen regimes in the North Atlantic. Three-dimensional modelling of the tetrameric haemoglobin structure demonstrated that the two amino acid replacements Met55β 1 Val and Lys62β 1 Ala are located at crucial positions of the α 1 β 1 subunit interface and haem pocket, respectively. The replacements are proposed to affect the oxygen-binding properties by modifying the haemoglobin quaternary structure and electrostatic feature. Intriguingly, the same molecular mechanism for facilitating oxygen binding is found in avian species adapted to high altitudes, illustrating convergent evolution in water- and air-breathing vertebrates to reduction in environmental oxygen availability. Cod populations inhabiting the cold Arctic waters and the low-oxygen Baltic Sea seem well adapted to these conditions by possessing the high oxygen affinity Val55–Ala62 haplotype, while the temperature-insensitive Met55–Lys62 haplotype predominates in the southern populations. The distinct distributions of the functionally different haemoglobin variants indicate that the present biogeography of this ecologically and economically important species might be seriously affected by global warming.

Responses to Hypersaline Exposure in the Euryhaline Crayfish PAcifastacus Leniusculus: II. Modulation of Haemocyanin Oxygen Binding In Vitro and In Vivo

1982 ◽  
Vol 99 (1) ◽  
pp. 447-467
Author(s):  
MICHÈLE G. WHEATLY ◽  
B. R. MCMAHON
Keyword(s):  
Salt Effect ◽  
Ionic Composition ◽  
Inorganic Ions ◽  
Pacifastacus Leniusculus ◽  
Oxygen Binding ◽  
Complete Saturation ◽  
O2 Delivery ◽  
O2 Binding

The effect of 48 h of hypersaline exposure (25, 50 and 75% SW) on haemocyanin oxygenation properties in the euryhaline crayfish Pacifastacus leniusculus was investigated in vitro and in vivo. In vitro significant increases in affinity and cooperativity were measured, although the magnitude of the Bohr shift was unaffected. In vitro dialysis of haemolymph against physiological salines of variable ionic composition proved that these changes were only partly attributable to altered levels of haemolymph ions, implicating the existence of modulators other than H+ and inorganic ions, the possible identities of which are discussed. Significant depressions of both pre- and postbranchial oxygen tensions (Pv, Ov, O2 and Pa, Oa, O2) were observed, but O2 delivery was maintained by utilization of the venous reserve and by an increase in haemocyanin O2 affinity. This occurred despite a concomitant acidosis whose effect on O2 affinity was directly opposed by the ‘salt’ effect. Under hypersaline conditions, haemocyanin played an increasingly important role in O2 delivery in vivo. Despite a reduction in the concentration of combined O2 at complete saturation of the pigment (CmaxHCyOHCyO2). indicating lowered haemocyanin concentration, compensatory changes in O2-binding and cardiac output precluded an impairment to O2 transfer. Equilibration at the tissues (Et,Ot,O2) in FW was less effective than at the gills (Eb,Ob,O2 but progressively improved with hypersaline exposure reversing this trend. Although effects of increased salinity on O2 equilibrium characteristics were qualitatively similar in vivo and in vitro, some interesting quantitative differences are discussed.

Mitochondrial function in the presence of myoglobin

1982 ◽  
Vol 53 (5) ◽  
pp. 1116-1124 ◽  
Author(s):  
R. P. Cole ◽  
P. C. Sukanek ◽  
J. B. Wittenberg ◽  
B. A. Wittenberg
Keyword(s):  
Oxygen Consumption ◽  
Steady State ◽  
Liquid Phase ◽  
Gas Phase ◽  
Oxygen Pressure ◽  
Oxygen Electrode ◽  
Oxygen Binding ◽  
Atp Production ◽  
Skeletal Muscle Mitochondria ◽  
The Difference

The effect of myoglobin on oxygen consumption and ATP production by isolated rat skeletal muscle mitochondria was studied under steady-state conditions of oxygen supply. A method is presented for the determination of steady-state oxygen consumption in the presence of oxygen-binding proteins. Oxygen consumed in suspensions of mitochondria was replenished continuously by transfer from a flowing gas phase. Liquid-phase oxygen pressure was measured with an oxygen electrode; the gas-phase oxygen concentration was held constant at a series of fixed values. Oxygen consumption was determined from the characteristic response time of the system and the difference in the steady-state gas- and liquid-phase oxygen concentrations. ATP production was determined from the generation of glucose 6-phosphate in the presence of hexokinase. During steady-state mitochondrial oxygen consumption, the oxygen pressure in the liquid phase is enhanced when myoglobin is present. Functional myoglobin present in the solution had no effect on the relation of mitochondrial respiration and ATP production to liquid-phase oxygen pressure. Myoglobin functions in this system to enhance the flux of oxygen into the myoglobin-containing phase. Myoglobin may function in a similar fashion in muscle by increasing oxygen flux into myocytes.

Self-association, cooperativity and supercooperativity of oxygen binding by hemoglobins.

1998 ◽  
Vol 201 (8) ◽  
pp. 1073-1084 ◽  
Author(s):  
A F Riggs
Keyword(s):  
Muscle Tissue ◽  
Buoyant Density ◽  
Fold Increase ◽  
Heme Iron ◽  
Common Mechanism ◽  
Oxygen Binding ◽  
Hypoxic Environment ◽  
Self Association ◽  
The Stability ◽  
O2 Binding

Cooperative ligand binding by tetrameric vertebrate hemoglobins (Hbs) makes possible the delivery of oxygen at higher pressures than would otherwise occur. This cooperativity depends on changes in dimer-dimer interactions within the tetramer and is reflected in a 50 000-fold increase in the tetramer-dimer dissociation constant in human Hb upon oxygenation at pH 7.4, from approximately 2x10(-11)mol l-1 to approximately 10(-6)mol l-1. Hbs that undergo such ligand-dependent changes in association are widespread in non-vertebrates, where the mechanisms are very different from those in vertebrates. Oligomeric Hbs have been identified in organisms in five phyla (molluscs, echinoderms, annelids, phoronids and chordates) that dissociate to subunits upon oxidation of the heme iron and reassociate with the binding of ferric iron ligands such as CN-, N3- or NO2-. Thus, the valence and ligand state of the heme iron control the stability of a critical subunit interface. The broad distribution of this phenomenon suggests a common mechanism of communication between heme and interface that may be almost universal among non-vertebrate Hbs. This interaction may be similar to that known for the homodimeric Hb of the mollusc Scapharca inaequivalvis. Although muscle tissue Hbs or myoglobins (Mbs) are usually monomeric, with non-cooperative O2 binding, the radular muscles of gastropod molluscs and chitons have homodimeric Mbs that bind O2 cooperatively. Cooperative non-muscle tissue Hbs have also been identified. These include the neural Hb of the nemertean worm Cerebratulus lacteus and the Hb of the diving beetle Anisops assimilis, which exhibit deoxygenation-dependent self-association of monomers that is associated with high Hill coefficients. Calculations suggest that the 2-3 mmol l-1 concentration of Hb on a heme basis in the brain of Cerebratulus should substantially extend the time as an active predator in an anaerobic or hypoxic environment. Oxygen from the Hb of Anisops is delivered to a gas bubble and thereby controls the buoyant density. Many Hbs of amphibians, reptiles, birds and some embryonic mammals exhibit a further 'supercooperativity' of O2 binding which depends on reversible deoxygenation-dependent tetramer-tetramer association to form an assemblage with a very low affinity for O2. This phenomenon results in steeper O2-binding curves than exhibited by tetramers alone. The increased cooperativity should result in an increase in the amount of O2 delivered to the tissues and should be especially valuable for avian flight muscles.

Sign in / Sign up

Export Citation Format

Share Document