Properties Of Hemocyanin Research Articles

Antitumor Activity of Glycosylated Molluscan Hemocyanins via Guerin Ascites Tumor

As observed in most molluscan hemocyanins, high-mannose type glycans were identified in hemocyanins from Rapana venosa (RvH), Helix lucorum (HlH) and keyhole limpet (Megatura crenulata). In addition, a glycan with a branching structure containing xylose, fucose and terminal methyl hexose was identified in β-HlH. We have examined the immuno-adjuvant properties of hemocyanins, their derivatives and conjugates associated with the cell mediated immunity in experimental tumor-bearing animals with ascites tumor of Guerin. After immunization of the animals with the experimental vaccine preparations, the highest values of splenic lymphocytes were observed in groups immunized with the conjugates RvH-TAg, β-HlH-TAg and KLH-TAg (42.3%; 40.8% and 40.58%, respectively) than with the native hemocyanins (36.5%; 35.1% and 32.4%, respectively). The immunization of rats with the hemocyanins β-HlH, RvH and KLH and their conjugates, prolonged the median survival time of tumor-bearing animals compared with non-immunized animals (39, 33, 31 and 7 days, respectively). Both hemocyanins β-HlH and RvH activate the immune system of the experimental animals and therefore could be a good alternative for KLH. For this reason they could be included into the composition of non-specific anti-tumor vaccines to enhance their effectiveness.

Identification, Structure, and Properties of Hemocyanins from Diplopod Myriapoda

Hemocyanins are copper-containing, respiratory proteins that occur in the hemolymph of many arthropod species. Here we report for the first time the presence of hemocyanins in the diplopod Myriapoda, demonstrating that these proteins are more widespread among the Arthropoda than previously thought. The hemocyanin of Spirostreptus sp. (Diplopoda: Spirostreptidae) is composed of two immunologically distinct subunits in the 75-kDa range that are most likely arranged in a 36-mer (6 x 6) native molecule. It has a high oxygen affinity (P(50) = 4.7 torr) but low cooperativity (h = 1.3 +/- 0.2). Spirostreptus hemocyanin is structurally similar to the single known hemocyanin from the myriapod taxon, Scutigera coleoptrata (Chilopoda), indicating a rather conservative architecture of the myriapod hemocyanins. Western blotting demonstrates shared epitopes of Spirostreptus hemocyanin with both chelicerate and crustacean hemocyanins, confirming its identity as an arthropod hemocyanin.

Haemocyanin oxygen binding and the physiological ecology of a range of talitroidean amphipods (Crustacea) I. pH, temperature, and l-lactate sensitivity

The effect of pH, temperature, and l-lactate on the O2 bindign properties of haemocyanin (Hc) from three talitroidean species i.e., the aquatic Apohyale pugettensis, the semi-terrestrial Megalorchestia californiana, and the semi-/euterrestrial Traskorchestia traskiana was studied. The Hc of A. pugettensis was characterized by a higher O2 affinity (and more pronounced Bohr shift) than the Hc of either M. californiana or T. traskiana. Apohyale was the only species that possessed He that was sensitive to temperature change. Resuspending Hc from each of the three species in a stock Ringer's solution (based on the ionic composition of the haemolymph of T. traskiana) showed that the persistence of the difference in Bohr shift between Apohyale and the other two species was due to differences in the haemocyanins themselves and not attributable to their respective ionic environments. An inverse relationship was found between the cooperativity (n50) and pH of Hc from T. traskiana and A. pugettensis but not for M. californiana. In each case adding l-lactate increased Hc O2 affinity, but this was most pronounced for A. pugettensis.

Structure and properties of hemocyanins: XII. Electron microscopy of dissociation products of Helix pomatia α-hemocyanin: Quaternary structure

Electron microscopy of the dissociation products of α-hemocyanin of the snail Helix pomatia reveals two distinctly different conformations of 1 10 -size molecules: a C(compact)-form at high ionic strength and pH near 8, and an L(loose)-form at low ionic strength and/or higher pH. The size and shape of the C- 1 10 -size molecules indicate a dissociation of the 1 2 -size molecules along the (10,9) helical grooves, which have been shown to be boundaries between the morphological units of the cylinder wall (Mellema & Klug, 1972). The 5-fold collar is distributed evenly among the C- 1 10 -size molecules. The C → L conformational change is characterized by a drastic loosening of the 1 10 -size molecules to a flexible cluster of globules, with a concomitant decrease of sedimentation coefficient and increase of intrinsic viscosity and frictional ratio. The 1 20 -size molecule appears as a flexible, linear chain of seven or eight globules with a diameter of 55 to 60 Å. These globules are inferred to be the minimal oxygen binding units with a molecular weight of about 50,000, linked together by short stretches of the polypeptide chain. Stable intermediate dissociation products, 2 10 , 3 10 and 4 10 -size molecules, were obtained by intramolecular crosslinking of 1 2 -size molecules with dimethyl-suberimidate prior to dissociation.

Oxygen-linked association-dissociation of Helix pomatia hemocyanin.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure and properties of hemocyanins. XV. Oxygen-linked association-dissociation of Helix pomatia hemocyaninRoel Van Driel and Ernst F. J. Van BruggenCite this: Biochemistry 1974, 13, 20, 4079–4083Publication Date (Print):September 1, 1974Publication History Published online1 May 2002Published inissue 1 September 1974https://doi.org/10.1021/bi00717a003RIGHTS & PERMISSIONSArticle Views26Altmetric-Citations16LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (565 KB) Get e-Alerts Get e-Alerts

Oxygen binding and subunit interactions in Helix pomatia hemocyanin.

Oxygen binding and subunit interactions in Helix pomatia hemocyanin.

Structure and properties of hemocyanins: VIII. Microheterogeneity of α-hemocyanin of Helix pomatia

The degree of dissociation of Helix pomatia α-hemocyanin is independent of its concentration. The dissociation products can be separated by ultracentrifugation or gel filtration. The isolated fractions do not reequilibrate. Subfractions of α-hemocyanin differ from total α-hemocyanin is a pH-dependent dissociation behaviour. It is suggested that α-hemocyanin is a population of closely similar molecular species differing in pH of dissociation. Independent evidence for microheterogeneity is obtained from reversible boundary spreading of α-hemocyanin and some of its dissociation products by electrophoresis on cellulose acetate.

Structure and properties of hemocyanins. V. Binding of oxygen and copper in Helix pomatia hemocyanin

1. 1. Reintroduction of monovalent copper into apo-α-hemocyanin of Helix pomatia leads to the complete return of the properties of native α-hemocyanin. 2. 2. The copper atoms in hemocyanin are required for the reassociation of tenth and twentieth molecules. 3. 3. In the reintroduction process, the copper atoms are randomly distributed among the empty binding sites of apo-α-hemocyanin. All copper-binding sites are equivalent and grouped in pairs; each pair forms a functional group. 4. 4. Upon storage for a few months, part of the copper atoms in every hemocyanin molecule are oxidized to Cu 2+. This affects the oxygenation properties. 5. 5. The oxygenation curves of fresh α- and β-hemocyanin are nonhyperbolic at alkaline pH values in the presence of Ca 2+ and Mg 2+. The influence of the pH on the oxygenation curves of α- and β-hemocyanin shows marked differences.

Structure and properties of hemocyanins: IV. Dissociation of Helix pomatia hemocyanin by succinylation into functional subunits

1. 1.|Hemocyanin of Helix pomatia was succinylated to various degrees with succinic anhydride. Evidence is given that not only the amino groups and the hydroxyl groups of tyrosine, serine and threonine were acylated but also the hydroxyl groups of the carbohydrate moiety of this protein. 2. 2.|Succinylation leads to dissociation of hemocyanin. Even at very low degrees of succinylation dissociation into twentieths (mol. wt. about 500 000) occurred; more exhaustive succinylation did not lead to smaller subunits. 3. 3.|Sedimentation and viscosity measurements, as well as electron microscopy, showed that these succinylated subunits had undergone considerable unfolding. 4. 4.|By progressive succinylation an increasing part of the Cu can be removed by EDTA; the residual Cu remains fully functional. Since 1 molecule of O 2 is bound per 2 atoms of Cu, this is evidence that the Cu atoms of each functional group are labilized simultaneously. 5. 5.|The cooperative interaction between the functional groups which is observed in native hemocyanin is completely lost upon succinylation.

Immunochemical properties of hemocyanin

Immunochemical properties of hemocyanin

Properties of hemocyanins—I. The effect of calcium ions on the oxygen equilibrium of crayfish hemocyanin

1. 1. The oxygen affinity of hemocyanin from the crayfish, Procambarus simulans, is greatly decreased by dialysis between pH 6·5 and 8·0. This effect is largely reversed by 10 mM calcium or by 60 mM magnesium. 2. 2. The data do not conform to Hill's equation, since the value of n increases with degree of oxygenation and is a function both of the calcium concentration and of pH. At low degrees of oxygenation n≅1·5 and is independent of pH or calcium, while at high oxygenation levels n increases with either pH or calcium. 3. 3. The importance of calcium in controlling the degree of dissociation of hemocyanin into subunits is known. Since the calcium concentration in crayfish blood changes during the molting cycle, it seems possible that calcium may play a role in modifying the oxygen transport function of hemocyanin by changing the degree of aggregation.

Structure and properties of hemocyanins: III. Electron micrographs of hemocyanins from different gastropoda and crustacea

Electron micrographs of negatively stained hemocyanin molecules of some Gastropoda (Helix pomatia, Buccinum undatum and Neptunea antiqua) and some Crustacea (Palinurus vulgaris, Homarus vulgaris, Nephrops norvegicus, Cancer pagurus and Carcinus maenas) were made. With the Gastropoda the molecular structure and dissociation at the alkaline side of the isoelectric point have been studied. Differences are observed between Helix p. and Buccinum u. on one hand and Neptunea a. on the other. The electron micrographs suggest that the first two hemocyanins are built from six equidistant parallel layers of subunits, while the latter consists of three double-layers of subunits. This makes a dissociation via half molecules highly improbable for Neptunea hemocyanin and thus explains the absence of the corresponding component on the sedimentation patterns. The molecular structures of the 16 s and 23 s component of the Crustacea hemocyanins were studied. The observed projections of the 16 s component are compatible with a molecular model consisting of eight subunits lying on the corners of a cube. The 23 s component is a dimer of two of these cubes.

Structure and properties of hemocyanins: I. Electron micrographs of hemocyanin and apohemocyanin from Helix pomatia at different pH values

Electron micrographs were made from Helix pomatia hemocyanin at different pH values with the negative-staining method. The pH-dependent dissociation on the alkaline side of the isoelectric point was especially studied. Our observations are in agreement with previously reported results, although they are not compatible with the model and mechanism of dissociation previously proposed. Our observations suggest that the Helix pomatia hemocyanin molecule is roughly cylindrical ; the diameter of the cylinder is about 300 Å and the height is about 335 Å. This cylinder has a fivefold axis; perpendicular to this axis it is built up from 6 parallel layers. The first dissociation step occurs perpendicular to the fivefold axis into halves. Further dissociation is supposed to be a splitting of these flat cylinders via submultiples into subunits. Divalent cations in concentrations of about 10−4 molar or higher are required for the reversibility of this dissociation.