Kinetically Inert Research Articles

Kinetically inert Co(III) linkage through an engineered metal binding site: Specific orientation of recombinant human papillomavirus type 16 E7 protein on a solid support

We report that engineered metal binding sites, or chelating peptides (CPs), can be used to site-specifically orient and immobilize recombinant CP-proteins on a solid support by forming a kinetically inert ternary complex with immobilized iminodiacetato-Co(III). The specific orientation and kinetic inertness of the linkage provide many advantages over conventional immobilization techniques. The utility of this novel immobilization chemistry was demonstrated using recombinant E7 protein from human papillomavirus type 16 with a CP, Met-His-Trp-His-His-His, at its N-terminus. The immobilized kinetically inert Co(III) complex of CP-E7 served as an extremely robust affinity matrix for the single-step purification of anti-E7 antibodies from rabbit antiserum. In addition, naturally occurring proteins that bind immobilized Co(II), such as myoglobin, can also be converted to kinetically inert immobilized complexes.

Effect of chromium(III) and of other ions on the absorptiometric determination of copper with 2, 2'-biquinolyl

In the determination of small amounts of copper in certain alloys by liquid-liquid extraction of the bis-chelate of copper(I) with 2, 2'-biquinolyl, recovery of copper has been reported to be low when chromium(III) is present. The adverse effect of chromium(III) could be overcome by adding iron(II). It is now shown that the inhibiting effect of chromium is attributable to the formation of a kinetically inert ternary complex of chromium(III), copper(II) and citrate ions containing an equal number of atoms of each of the two metals. Copper can be displaced from this complex by any of the transition cations Mn(II), Fe(II), Co(II), Ni(II) and Zn(II). Zinc is shown to form a ternary complex formally analogous to that of copper. The formation of the ternary complexes has been studied polarographically. The formation of binuclear complexes of various hydroxy-acids is reviewed and a probable structure for the ternary complex is proposed which explains its stability and kinetic inertness. Analogies are drawn between this complex and ternary complexes of UO(2)(VI)-Al(III)-citrate and Cu(II)-Al(III)-tartrate which also cause interference in established analytical procedures.