Figure 4.

Chain composition of the two-chain TPI from N. attenuata. A, Separation of the chains. The purified two-chain TPI (5 μg) was reductively carboxymethylated, and the liberated chains were purified by RP-HPLC (solid line). The position of the original two-chain TPI (1 μg) is indicated (dashed line). The chromatography was performed on a C₄ Vydac column equilibrated in 0.1% (v/v) TFA, eluted with acetonitrile gradient (dotted line), and monitored by A₂₂₀. B, The deduced covalent structure of the two-chain TPI. The A1 chain is N-terminally trimmed (see A1-K and A1-A peaks in A). The Gln residue in A2 chain is modified to pyroglutamic acid (<Q). The Asn residue in the consensus glycosylation signal (underlined) contains an N-linked oligosaccharide. The interchain disulfides are connected according to those known from homologous PI-II inhibitors.