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Biomedical subjects

D E Green

Publications and source records attributed to D E Green.

At least 73 records · Page 4Linked to original sources
PubMed1980

Relation between enzymic catalysis and energy coupling.

The principles that underlie enzyme catalysis also apply to energy coupling processes. A comparison is made between a kinase system that mediates the phosphorylation of glucose by ATP (hexokinase), as the prototype for enzymic catalysis, and the mitochondrial electron-transfer complexes, as the prototypes for energy coupling systems. Induced polarization of chemical bonds and charge separation and elimination are common component events of both enzyme catalysis and energy coupling. Thus, definite limits can be imposed on models of energy coupling; they must comply with the basic principles of enzymic catalysis.

Binding Sites↗
PubMed1980

Ion-transport chain of cytochrome oxidase: the two chain-direct coupling principle of energy coupling.

Cytochrome oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1) couples the aerobic oxidation of ferrocytochrome c to the cyclical transport of monovalent cations or to the active transport of monovalent and divalent cations. This transport capability is mediated by an intracomplex ion-transport chain of two protein-bound molecules of cardiolipin per molecule of cytochrome oxidase. Cardiolipin in a two-phase system shows the identical ionophoric pattern as does the cytochrome oxidase coupled system. A molecular model of the cardiolipin chain suggests the possibility of a cage-like structure through which cations can be transferred from phosphate group to phosphate group. The ion-transport chain and the electron-transport chain are anchored to the same set of subunits (I+IV); the close proximity of the two chains argues for the direct coupling of electron and cation flow. The ion-transport chain of cytochrome oxidase provides an introduction to the molecular mechanisms by which ions are moved across membranes in energy-coupling systems.

Amino Acids↗
PubMed1980

On reagents that convert cytochrome oxidase from an inactive to an active coupling state.

Cytochrome oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1) of beef heart mitochondria, prepared by a standard method and brought to the highest purity level, is essentially inactive when tested in the aerobic assay involving oxidation of reduced cytochrome c by molecular oxygen. Three reagents (lysolecithin, Tween 20, and exogenous phospholipids) can convert cytochrome oxidase from an inactive to an active coupling state. These conversions are reversible: i.e., removal of the inducing agent leads to loss of activity. The evidence for the intrinsic coupling capability is that cytochrome oxidase in the active state invariably generates a proton gradient during respiration, and such gradient formation is demonstrable even when cytochrome oxidase is not inserted into a liposome.

Animals↗
PubMed1980

Maturation of humoral immune response determines the susceptibility of guinea-pigs to leptospirosis.

Baby guinea-pigs were susceptible to infection with Leptospira interrogans serovar pomona, but rapidly became resistant as they matured. Increased resistance with increasing weight of guinea-pigs was correlated with the development of ability to produce agglutinating antibodies to leptospires and with maturation of B-cell dependent (but not T-cell dependent) areas in lymphoid organs. These observations can explain the basis of species-resistance of adult guinea-pigs to infection with serovar pomona.

Aging↗
PubMed1979

Ion-channel component of cytochrome oxidase.

Cytochrome oxidase is resolvable into an electron transfer complex and an ion transfer complex. The ion transfer complex has been shown to have the capability for inducing nonspecific ion transport into liposomes. Subunit I of cytochrome oxidase has been identified as an ion-channel-forming protein.

Biological Transport, Active↗
PubMed1979

Patterns of tobacco use in the United States.

Overall, then, the picture of decrease in cigarette smoking is an encouraging one, with the exception of the increased rate of smoking among teenage girls. However, this change probably reflects the tenor of the times and an alteration in the concept of what has traditionally been considered "feminine" behavior.

Adolescent↗
PubMed1978

Resolution of complex III of the mitochondrial electron transfer chain into two component complexes.

Complex III can be resolved into an electron transfer complex and an ion transfer complex. The electron transfer complex contains exclusively the oxidation-reduction proteins of complex III, and the ion transfer complex the capability for augmenting cation-induced fluorescence of 8-anilino-1-naphthalenesulfonic acid. This finding has important implications for the molecular mechanism of mitochondrial energy coupling.

Animals↗
PubMed1978

Resolution of cytochrome oxidase into two component complexes.

Cytochrome c oxidase (ferrocytochrome c: oxygen oxidoreductase, EC 1.9.3.1) has been resolved into a pair of complexes of unequal molecular weight. The larger complex (electron transfer complex) contains exclusively the oxidation-reduction proteins characteristic of cytochrome oxidase; the smaller complex (ion transfer complex) shows exclusively the capability for cation-dependent induction of the fluorescence of 8-anilino-1-naphthalenesulfonic acid--a capability demonstrable in preparations of cytochrome oxidase. The duplex nature of cytochrome oxidase has important implications for the mechanism of energy coupling.

Copper↗