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Biomedical subjects

G Zimmer

Publications and source records attributed to G Zimmer.

At least 163 records · Page 9Linked to original sources
PubMed1978

[Biochemical and clinical studies on the influence of 2-mercaptopropionylglycine on liver cell function (author's transl)].

2-Mercaptopropionylglycine was used for the treatment of chronic hepatitis. The drugs showed very good clinical results. In biochemical studies it was found that there was no effect on phosphate transport. Instead, there was an increase of reactive SH-groups sensitive to oligomycin in the membrane of rat liver mitochondria. The ATPase activity in mitochondria was diminished, while ATP-contents of the mitochondrial suspensions were increased by the drug. In the presence of ATP-MG++ there was an increase of oligomycin-sensitive contraction of the mitochondria. In aged mitochondria, the P/O ratios were improved. Reversal of electron transport with formation of NADH by succinate in the presence of rotenone and ATP was, concentration dependently, improved by MPG. Thus, MGP obviously acts at some specific sulfhydryl groups of the mitochondrion. It is concluded that the action of the drug in chronic hepatitis may be interpreted via an improvement of mitochondrial function.

Adenosine Triphosphatases↗
PubMed1978

ATP contents and structure of rat liver mitochondria in the presence of 2-mercaptopropionylglycine.

2-Mercaptopropionylglycine was found to be efficient in the treatment of chronic hepatitis. Interest was focussed on the possible mode of action of that reagent at the subcellular level. ATP contents in mitochondria were increased after anaerobic preincubation and after addition of ADP and 2-mercaptopropionylglycine. Concomitantly, we found an increase in condensed configuration of mitochondria. If the reagent was added before ATP-Mg2+ (ADP) the mitochondrial structure was well preserved, though, throughout of orthodox configuration. In comparison the control specimens were grossly swollen. It is proposed that the reagent may act at the level of mitochondrial energy coupling.

Adenosine Triphosphate↗
PubMed1977

Oligomycin sensitivity of mitochondrial sulfhydryl groups.

Dithionitrobenzoate has been used to titrate sulfhydryl groups of rat liver mitochondria in glutamate buffer, pH 7.4. Reaction with oligomycin and different SH reagents preceded the SH titration. Under these conditions it was found that 2-mercaptopropionylcne and N-ethylmaleimide reacted in an oligomycin-sensitive manner, so that the control values (in the absence of SH reagent) were obtained. Similar concentrations of mersalyl and of N-(N-acetyl-4-sulfamoylphenyl) maleimide, in the presence of oligomycin, enhanced reactivity toward Nbs2. The concentration range of oligomycin-sensitive SH groups was thus defined between approx. 5 and 9 nmol reagent/mg mitochondrial protein. In this way, a differentiation between SH grops, which are implicated in phosphate transport antd those, which react in an oligomycin-sensitive manner, and which are probably connected with the coupling mechanism was achieved.

Animals↗
PubMed1976

Conformation and reactivity of DNA in the complex with protein. IV. Circular dichroism of poly-L-histidine model complexes with DNA polymers and specificity of the interaction.

The CD study of the DNA-poly-L-histidine complex at high degree of protonation revealed that complex formation is already observable at 2 M NaCl. The influence of salt together with 5 M urea suggests that in addition to electrostatic interactions probably hydrogen bonding may favour specific complexes. Affinity of protonated histidines to AT-rich regions is strongly supported by the complexes formed with (dA.dT)-containing polymers. The psi-type structure occurs with poly(dA-dT)-poly(dA-dT) while poly(dA)-poly(dT) is restricted to form a similar psi-state on interaction with highly protonated poly-L-histidine. Differences in the helix winding properties due to variation in the sequence is suggested as a possible factor in the formation of the psi-type complexes. The mechanism of interaction including hydrogen bonding of histidine side-chains with an AT pair at high degree of protonation and with GC-regions at lower degree of protonation in the polypeptide structure is discussed.

Binding Sites↗
PubMed1975

Lipid-protein interactions at the erythrocyte membrane. Different influence of glucose and sorbose on membrane lipid transition.

When observed over a temperature range, erythrocyte membrane lipids undergo a transition at 18-20 degrees C (Zimmer, G. and Schirmer, H. (1974) biochim. Biophys. Acta 345, 314-320). This observation has prompted an investigation of the effects that substrate binding has on the transition of the red cell membrane. Glucose and sorbose were compared, since transport kinetics of these sugars still pose unresolved questions. In membranes, preloaded with glucose, the break at the transition temperature was intensified, while it was abolished or reversed in membranes preloaded with sorbose. These results were corroborated using different solubilization procedures (sonication, sodium dodecyl sulfate treatment) of the membranes, and also different techniques (viscosimetry, 90 degrees light scattering, 1-anilino-naphthalene-8-sulfonate fluorescence). In extracted membrane lipids, viscosimetry indicated a break at transition temperature after preloading with either glucose or sorbose. Disc electrophoresis revealed a different binding pattern of the two sugars. It is suggested, that the amplification of the discontinuity in red cell membranes by glucose and the abolition or reversal of the break by sorbose are mediated by membrane protein- and/or membrane lipid-protein interaction.

Blood Proteins↗