Panulirus interruptus hemocyanin

Abstract

The primary structure of subunit b of Panulirus interruptus hemocyanin has been derived from two digests (trypsin and CNBr) and, in some cases, with aid from the similarity with the sequence of subunit a. Differences between the amidation states of Asx and Glx residues in subunit b relative to a were investigated more thoroughly. When compared to the sequence of subunit a, 18 differences (2.7%) were found and certain heterogeneities, indicating the presence of a minor subunit b', were observed.Several differences in properties between subunits a and b, including their anomalous behaviour on SDS/ polyacrylamide gel electrophoresis, could be explained by amino acid replacements.Hemocyanins are large multi-subunit copper-containing oxygen carriers occurring freely dissolved in the hemolymph of many molluscs and arthropods. Arthropod hemocyanins are composed of hexamers or multi-hexamers with subunits of about 75 kDa, each of which contains one binuclear copper site 11, 21. As in all arthropods, hemocyanin of the spiny lobster Punulirus interruptus displays subunit heterogeneity Both X-ray diffraction and amino acid sequence studies have also been performed. Subunits a and b, accounting for 80 -90% of the monomers upon dissociation of the hexamers, are very similar, but subunit c is quite different [3, 6-81. The complete amino acid sequence of subunit a has been published recently [9]. The three-dimensional structure has been determined at 0.32-nm resolution [4, 101. Since the latter study was performed with crystals containing a mixture of subunits a and b in roughly equal amounts [4, lo], knowledge of the amino acid sequence of subunit b is essential for a reliable interpretation of the electron-density map. Furthermore, comparison of the primary structures of subunit a and b may explain the difference in their apparent molecular masses on SDS/polyacrylamide gels.

Nucleotide sequence of the cDNA encoding the proenzyme of phenol oxidase A1 of Drosophila melanogaster.

“…The reason for this discrepancy is unclear. Possibly asparagine in certain amino acid sequences is liable to be deamidated during the sequencing procedure, as has been shown for Panulirus hemocyanin (17). No hydrophobic sorting signal sequence for the endoplasmic reticulum is found in the NH2-terminal region.…”

“…(37) Rzoum mecild (trouina) . FPanuirdls baerruq (hemocyanin subunit b) (17) Panns aips (hemocyanin subunit a ) (30) Pamulrus baterrupus (hemocyanin subunit c ) (31) Tachpes rldeAu (hemocyanin subumit a) Ewyp_m calbrcm (hemoyaniln subunit c) (27) Liwuspoyphmus (hemocanin II) (29) Ewuypebn calNornkm (hemocyanin subunit a)(27) Ewypebma califokncm (hmocyanin subunit d) (28) Pac#faacus kelscodus po1pchnoloxdas) (26) Manduca sepa (ewloxddase) Banbyxmon (prophenolaxidase polypepde II) (25) Bombyx mon (prophenoloxidasc polypeptide 1) (25) -Drosoa mkelanogast (prophenoloxidase A1) Amino Acid Sequence Homologies. A search of Swiss-Prot revealed significant sequence similarity of pro-PO A1 to hemocyanins of arthropod (Fig.…”

Subunits composition and allosteric control in Carcinus aestuarii hemocyanin

“…Various studies elucidate the subunit composition of crustacean Hc. In general, three subunits are found namely a, b and c subunits (Bak and Beintema, 1987;Jekel et al, 1988; Neuteboom et al, 1992;Markl, 1986). They are differently expressed in the various species (Mangum, 1993) and are necessary to guarantee the specific aggregation state (Markl and Decker, 1992).…”

cDNA cloning of prophenoloxidase from the freshwater crayfish Pacifastacus leniusculus and its activation.

“…To obtain the sequence of the complete open reading frame a PCR method (see Fig. 2 (29), hemocyanin b from the spiny lobster Panulirus interruptus (30), and tyrosinases from human (31), mouse (32), the frog Rana nigromaculata (33), the fungus Neurospora crassa (34), and the bacterium Streptomyces antibioticus (35). Amino acids found in identical positions in proPO and the other proteins are boxed.…”