Biological oxidation, theory

Other proposed mechanisms for the effects of isoflavones include the prevention of atheroma formation through their antioxidant ability, and recently, the oxidative theory of atherogenesis has provided another avenue of therapy involving antioxidants [129], According to this theory, antioxidants should protect lipoproteins against oxidative modification and reduce the biological consequences. Thus, Tikkanen et al [130] showed that the intake of soy protein containing 60 mg of isoflavones per... 

An informative and entertaining personal account of the development of his theories was published by A. Szent-Gydrgyi as a small monograph Studies on Biological Oxidation. Karl Reaugi, Leipzig, 1937. 

Why do we grow old Despite advances in molecular biology and medical research, the reasons for aging remain mysterious. One theory suggests that aging may be influenced by oxidizing agents, also known as oxidants. 

Most of biological chemistry can be understood in terms of simple ball and stick models. The chemistry of nitric oxide and related oxides is more intimidating because its patterns of bonding depend strongly on quantum mechanics and molecular orbital theory. But the basics can be grasped by comparison to other molecules and a simple consideration of where nitrogen sits in the periodic table. 

Chemiosmotic theory provides the intellectual framework for understanding many biological energy transductions, including oxidative phosphorylation and photophosphorylation. 

In Ihis chapter the theories developed previously will be used 10 help correlate the important facts of the chemistry of groups 1—12 Much of the chemistry of these elements, in particular the transition metals, has already been included in the chapters on coordination chemistry (Chapters II, 12, and 13). More will be discussed in the chapters on organometaJlic chemistry (Chapter 15), clusters (Chapter 16), and the descriptive biological chemistry of the transition metals (Chapter 19). The present chapter will concentrate on the trends within the series (Sc to Zn, Y to Cd, Lu to Hg, La to Lu, and Ac to Lr), the differences between groups (Ti — Zr - Hf Cu — Ag - Au), and the stable oxidation stales of the various metals. 

The theory of electron transfer in chemical and biological systems has been discussed by Marcus and many other workers 74 84). Recently, Larson 8l) has discussed the theory of electron transfer in protein and polymer-metal complex structures on the basis of a model first proposed by Marcus. In biological systems, electrons are mediated between redox centers over large distances (1.5 to 3.0 nm). Under non-adiabatic conditions, as the two energy surfaces have little interaction (Fig. 5), the electron transfer reaction does not occur. If there is weak interaction between the two surfaces, a, and a2, the system tends to split into two continuous energy surfaces, A3 and A2, with a small gap A which corresponds to the electronic coupling matrix element. Under such conditions, electron transfer from reductant to oxidant may occur, with the probability (x) given by Eq. (10),... 

---