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Biomedical subjects

L Packer

Publications and source records attributed to L Packer.

At least 415 records · Page 23Linked to original sources
PubMed1976

Inactivation and reactivation of mitochondrial respiration by charged detergents.

Respiration of submitochondrial preparations can be inhibited by the cationic detergent cetyl trimethyl ammonium bromide and the anionic detergent sodium dodecyl sulfate in the range of 0.3-2 mumol of detergent per mg of mitochondrial membrane protein depending on the substrate and detergent used. This inhibition can be rapidly reversed by neutralizing a given detergent by the detergent of the opposite charge. At higher levels of the inhibiting detergent, no such reactivation was observed. Spin labeling assays of membrane structure were used to correlate structural effects with the loss and recovery of respiratory functions. Because the detergents progressively disrupt membrane structure, mitochondrial were cross-linked with bifunctional imidoesters to an extent that osmotic properties and detergent lysis were gone, but respiration remained. Such fixed respiring mitochondria also show inhibition reactivation phenomena.

Binding, Competitive↗
PubMed1976

Analysis of freeze-fracture electron micrographs by a computer-based technique.

A procedure is described for deriving a numerical characterization of membrane particle patterns revealed in freeze-fracture electron micrographs. Rectangular coordinates of the particles are obtained with high precision by means of an electronic digitizing device. These coordinates are fed into a large computer and analyzed in terms of (alpha) a local particle density function in terms of variable subdivisions of the membrane, and (beta) an interparticle distance function describing describing all particle pairs within the membrane. It is found that the particle density function gives the most useful description of clustering provided that particle-free patches are monitored along with nonvanishing particle densities. Theoretical particle patterns are generated with the computer by means of a random number generator to provide defined aggregation states which serve as standards of comparison for observed particle patterns.

Cell Line↗
PubMed1975

Effect of crosslinking on mitochondrial structure and function.

Rat liver mitochondria were treated with ethylacetimidate and methylbutyrimidate, monofunctional imidates, and with dimethylsuberimidate, a bifunctional imidate, and the effects on structure and function studied. Mitochondria treated with 5 mM dimethylsuberimidate or greater did not respond osmotically when placed in deionized water. Sodium dodecylsulfate-polyacrylamide gel electrophoresis revealed that at concentrations greater than 5 mM dimethylsuberimidate nearly all mitochondrial polypeptides failed to enter 6% gels, indicating crosslinking of both membrane and soluble proteins. Extensive amidination by ethylacetimidate and methylbutyrimidate had little effect on ascorbate-tetramethylphenylenediamine oxidase while extensive inhibition resulted from dimethylsuberimidate treatment. The possible involvement of molecular motion in electron transport is discussed.

Alkylating Agents↗
PubMed1975

Dimethyl adipimidate: a new antisickling agent.

A new approach to the prevention of sickling in vitro by use of the bifunctional crosslinking reagent, dimethyl adipimidate, is described. Prior treatment of sickle erythrocytes with dimethyl adipimidate will inhibit sickling in completely deoxygenated erythrocytes. Treated erythrocytes do not demonstrate the potassium loss and viscosity increase that usually accompany sickling. The oxygen affinity of hemoglobin in these cells is increased independently from changes in the concentration of 2,3-diphosphoglycerate. The hemoglobin obtained from treated erythrocytes contains a high-molecular-weight component as well as additional positively charged components. The relative degree to which chemical modification and/or crosslinking is an essential part of the antisickling properties of the material is not known.

Adipates↗