Reactive oxygen species are known to be potentially dangerous, but are also needed for signal-transduction pathways. Tumor cells have relatively low amounts of superoxide dismutase (SOD), which quenches superoxide anion (O2 •), and as a result of a higher level of aerobic metabolism, higher concentrations of O2 •, compared to normal cells. But this may not be true of all tumor cells. Some tumor...

Skeletal muscle troponin C (TNC) is structured into two separate domains linked by a nine-turn alpha-helix (D/E helix). It has been demonstrated that calcium binding to the regulatory sites within the N-terminal domain induces conformational changes in the C-terminal domain of isolated TNC. Since the only contact between the two domains is the long D/E helix, the transfer of information must in...

Fouquet, J.-L. and A.P. Wojda, Mutual placement of bipartite graphs, Discrete Mathematics 121 (1993) 85-92. Let G =(L, R, E) and H =(L’, R’, E’) be bipartite graphs. A bijection 4: L w R + L’v R’ is said to be a biplacement of G and H if 4(L)= L’ and ~$(x)~$(y)gE’ f or every edge xy of G. A biplacement of G and its copy is called a 2-placement of G. We prove that, with some exceptions, every bi...