The amino acid sequence of hemoglobin III from the symbiont-harboring clamLucina pectinata

Abstract

The cytoplasmic hemoglobin III from the gill of the symbiont-harboring clam Lucina pectinata consists of 152 amino acid residues, has a calculated Mm of 18,068, including heme, and has N-acetyl-serine as the N-terminal residue. Based on the alignment of its sequence with other vertebrate and nonvertebrate globins, it retains the invariant residues Phe45 at position CD1 and His98 at the proximal position F8, as well as the highly conserved Trp16 and Pro39 at positions A12 and C2, respectively. The most likely candidate for the distal residue at position E7 is Gln66. Lucina hemoglobin III shares 95 identical residues with hemoglobin II (J. D. Hockenhull-Johnson et al., J. Prot. Chem. 10, 609-622, 1991), including Tyr at position B10, which has been shown to be capable of entering the distal heme cavity and placing its hydroxyl group within a 2.8 A of the water molecule occupying the distal ligand position, by modeling the hemoglobin II sequence using the crystal structure of sperm whale metmyoglobin. The amino acid sequences of the two Lucina globins are compared in detail with the known sequences of mollusc globins, including seven cytoplasmic and 11 intracellular globins. Relative to 75% homology between the two Lucina globins (counting identical and conserved residues), both sequences have percent homology scores ranging from 36-49% when compared to the two groups of mollusc globins. The highest homology appears to exist between the Lucina globins and the cytoplasmic hemoglobin of Busycon canaliculatum.

Globin and Globin Gene Structure of the Nerve Myoglobin of Aphrodite aculeata

“…Lys(CD4) and Lys(E10) might also form salt bridges with the heme propionates. The occupation of E11 by Phe is only shared in the Calyptogenae soyoae and Lucina pectinaria hemoglobins, two globins having a heme environment exceptionally rich in aromatic amino acids (31)(32)(33)). …”

Thermal Fluctuations in Systems with Continuous Symmetry

“…Printed in Great Britain -all rights reserved Hb II consists of 150 amino acids and has a calculated molecular weight of 17476, including heme and an acetylated N-terminal residue . Hb III consists of 152 amino acids and has a calculated molecular weight of 18068, including heme and an acetylated N-terminal residue (Hockenhull-Johnson et al, 1994). The two hemoglobins share 95 identical residues.…”

SAXS structure of homodimeric oxyHemoglobin III from bivalve Lucina pectinata

“…These kinetic studies support the idea that both HbII and HbIII can work as oxygen transport proteins [ 4 ] and that such transport could occur via the HbII‐HbII and HbIII‐HbIII homodimers and HbII‐HbIII heterodimer states. The primary structure of HbIII consists of 152 residues, [ 6,7 ] with a molecular weight of 18 068 Da, including the heme group. The molecular weight of HbII is 17 654 Da, again including the heme group.…”