Hemocyanins in Spiders, XVIII. Complete amino-acid sequence of subunit e from Eurypelma californicum hemocyanin.

The complete amino-acid sequence of subunit e of the hemocyanin from the tarantula, Eurypelma californicum, was determined by a combination of manual and automated methods. By limited proteolysis with chymotrypsin, two large fragments (e-CHn 29 and e-CHn 42) were obtained. The large peptides were further cleaved with cyanogen bromide, trypsin (with and without prior blocking of lysine residues), chymotrypsin, Staphylococcus aureus proteinase, Astacus fluviatilis proteinase, or 25% formic acid. The complete chain comprises 621 residues. A remarkable feature of the sequence is a hexapeptide -His-His-Trp-His-Trp-His- which is believed to take part in the binding of copper.