[This corrects the article on p. 100 in vol. 41.].

Energy conservation in chemotrophic anaerobic bacteria.

50 years ago Peter Mitchell proposed the chemiosmotic hypothesis for which he was awarded the Nobel Prize for Chemistry in 1978. His comprehensive review on chemiosmotic coupling known as the first "Grey Book", has been reprinted here with permission, to offer an electronic record and easy access to this important contribution to the biochemical literature. This remarkable account of Peter Mitchell's ideas originally published in 1966 is a landmark and must-read publication for any scientist in the field of bioenergetics. As far as was possible, the wording and format of the original publication have been retained. Some changes were required for consistency with BBA formats though these do not affect scientific meaning. A scanned version of the original publication is also provided as a downloadable file in Supplementary Information and can be found online at doi:10.1016/j.bbabio.2011.09.018. See also Editorial in this issue by Peter R. Rich. Original title: CHEMIOSMOTIC COUPLING IN OXIDATIVE AND PHOTOSYNTHETIC PHOSPHORYLATION, by Peter Mitchell, Glynn Research Laboratories, Bodmin, Cornwall, England.

Chemiosmotic coupling in oxidative and photosynthetic phosphorylation

For present purposes, a protein-bound metal site consists of one or more metal ions and all protein side chain and exogenous bridging and terminal ligands that define the first coordination sphere of each metal ion. Such sites can be classified into five basic types with the indicated functions: (1) structural -- configuration (in part) of protein tertiary and/or quaternary structure; (2) storage -- uptake, binding, and release of metals in soluble form: (3) electron transfer -- uptake, release, and storage of electrons; (4) dioxygen binding -- metal-O{sub 2} coordination and decoordination; and (5) catalytic -- substrate binding, activation, and turnover. The authors present here a classification and structure/function analysis of native metal sites based on these functions, where 5 is an extensive class subdivided by the type of reaction catalyzed. Within this purview, coverage of the various site types is extensive, but not exhaustive. The purpose of this exposition is to present examples of all types of sites and to relate, insofar as is currently feasible, the structure and function of selected types. The authors largely confine their considerations to the sites themselves, with due recognition that these site features are coupled to protein structure at all levels. In themore » next section, the coordination chemistry of metalloprotein sites and the unique properties of a protein as a ligand are briefly summarized. Structure/function relationships are systematically explored and tabulations of structurally defined sites presented. Finally, future directions in bioinorganic research in the context of metal site chemistry are considered. 620 refs.« less

/pdf/structural-and-functional-aspects-of-metal-sites-in-biology-a6d65lev8n.pdf

Structural and Functional Aspects of Metal Sites in Biology

Indirect evidence suggests accelerated degradation of endothelium-derived nitric oxide (ENDO) by superoxide anion (O2-) in hypercholesterolemic vessels (HV) To directly measure O2- production by normal vessels (NV) and HV, we used an assay for O2- based on the chemiluminescence (CL) of lucigenin (L) HV (1 mo cholesterol-fed rabbits) produced threefold more O2- than NV (147 +/- 020 nM/mg tissue/min, n = 7 vs 052 +/- 005 nmol/mg tissue/min, n = 8, P < 0001) Endothelial removal increased O2- production in NV (073 +/- 008, n = 6, P < 005), while decreasing it in HV (076 +/- 015, n = 5, P < 005) There was no difference between denuded HV and denuded NV Oxypurinol, a noncompetitive inhibitor of xanthine oxidase, normalized O2- production in HV, but had no effect in NV In separate isometric tension studies treatment with oxypurinol improved acetylcholine induced relaxations in HV, while having no effect on responses in normal vessels Oxypurinol did not alter relaxations to nitroprusside Thus, the endothelium is a source of O2- in hypercholesterolemia probably via xanthine oxidase activation Increased endothelial O2- production in HV may inactivate endothelium-derived nitric oxide and provide a source for other oxygen radicals, contributing to the early atherosclerotic process

/pdf/hypercholesterolemia-increases-endothelial-superoxide-anion-1rnwngjon2.pdf

Hypercholesterolemia increases endothelial superoxide anion production.

We have evaluated the role of nitric oxide (NO) on the activity of the constitutive and induced forms of cyclooxygenase (COX; COX-1 and COX-2, respectively). Induction of NO synthase (NOS) and COX (COX-2) in the mouse macrophage cell line RAW264.7 by Escherichia coli lipopolysaccharide (1 microgram/ml, 18 h) caused an increase in the release of nitrite (NO2-) and prostaglandin E2 (PGE2), products of NOS and COX, respectively. Production of both NO2- and PGE2 was blocked by the NOS inhibitors NG-monomethyl-L-arginine or aminoguanidine. The effects of NG-monomethyl-L-arginine or aminoguanidine were reversed by coincubation with L-Arg, the precursor for NO synthesis, but not by D-Arg. RAW264.7 cells stimulated for 18 h with lipopolysaccharide in L-Arg-free medium (to reduce NO generation by the endogenous NOS pathway) failed to release NO2- and accumulated at least 4-fold less PGE2 when compared to cells in the presence of L-Arg. PGE2 production elicited by a 15-min arachidonic acid treatment of lipopolysaccharide-induced RAW264.7 cells in L-Arg-deficient medium was decreased 3-fold when compared to the release obtained with cells induced in medium containing L-Arg. To examine the NO activation of the induced form of COX in the absence of an endogenous L-Arg, human fetal fibroblasts were first stimulated for 18 h with interleukin 1 beta. These cells released PGE2 but not NO2-, consistent with the induction of COX but not NOS in the fibroblast. Exogenous NO either as a gaseous solution or released by a NO donor, sodium nitroprusside or glyceryl trinitrate, increased COX activity in the interleukin 1 beta-stimulated fibroblasts by 5-fold; these effects were abolished by coincubation with hemoglobin (10 microM), which binds and inactivates NO, but not by methylene blue, an inhibitor of the soluble guanylate cyclase. Furthermore, sodium nitroprusside (0.25-1 mM) increased arachidonic acid-stimulated PGE2 production by murine recombinant COX-1 and COX-2. These results demonstrate that NO enhances COX activity through a mechanism independent of cGMP and suggest that, in conditions in which both the NOS and COX systems are present, there is an NO-mediated increase in the production of proinflammatory prostaglandins that may result in an exacerbated inflammatory response. The data suggest that NO directly interacts with COX to cause an increase in the enzymatic activity.

https://www.pnas.org/content/pnas/90/15/7240.full.pdf

B.F. Van Gelder

Papers

The extinction coefficient of cytochrome c.

On cytochrome c oxidase I. The extinction coefficients of cytochrome a and cytochrome a3

Demonstration by EPR spectroscopy of the functional role of iron in soybean lipoxygenase-1

Isolation procedure and some properties of myeloperoxidase from human leucocytes

Generation of superoxide radicals during the autoxidation of mammalian oxyhemoglobin