Structure and Function of Baboon Hemoglobins

Structural characterization of seven different subunits in Androctonus australis haemocyanin

“…The existence of an eighth was discussed above and seems probable. The heterogeneity of the haemocyanin constituents had been demonstrated by several methods such as ion exchange chromatography [6], sodium dodecylsulfate polyacrylamide gel electrophoresis [7], immunochemistry [2], genetics [8] and peptide mapping [9] but this work is, to our knowledge, the first to prove that the sequences of the polypeptide chains are different at least in their N-terminal parts.…”

The reaction of azide with Limulus polyphemus methaemocyanin

“…This fractional number might be due to differences in the reaction of the subunits of L. polyphemus methaemocyanin with azide. The subunits were isolated by chromatography on DEAE-Sephadex A-50 with a sodium chloride gradient [5], brought to pH 5.0 by dialysis and treated with hydrogen peroxide as described. The methaemocyanin obtained with fractions I and II gave only a faint reaction with azide, the methaemocyanin of fraction IV treated with azide showed no circulardichroic bands at 423 nm and 356 nm after 15 min, while the methaemocyanin from fraction III and V gave a pronounced reaction with azide.…”

Translation of mRNA for Limulus polyphemus Haemocyanin Polypeptides in vitro: Studies on Subunit Heterogeneity

“…[2] showed that a significant difference exists in the inethionine content of the chromographically separated zones I -V. Such differences, resulting in differential labelling of the polypeptides, may account for the inability do detect some polypeptides in the system used. (e) Some polypeptides may in fact arise by modification of other synthesised polypeptides.…”

“…The native circulating molecules may be composed of one, two, four or eight 'hexameric units', each of which is built up from six polypeptides, depending upon the species [I]. The haemocyanin of the xiphosuran Limulus polyphemus is one of the largest arthropod haemocyanins and contains 48 polypeptides with M , 65 000 -70000 [2]. The subunits are heterogeneous [3,4] and currently at least fifteen subunits with molecular weights in this range have been identified by electrophoretic and immunological characterisation [S].…”

“…[2] does subunit heterogeneity arise from the synthesis of several different polypeptides or from post-translational modification of a single, or a subset of, polypeptides?, and [3] can data from translation of mRNA in vitro be correlated with possible release mechanisms from the cyanoblasts in vivo? Translation products of Limulus mRNA synthesised in both the reticulocyte lysate cell-free system and in Xenopus oocytes were characterised by immunological and electrophoretic methods.…”