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Biomedical subjects

A Hüttermann

Publications and source records attributed to A Hüttermann.

At least 37 records · Page 2Linked to original sources
PubMed1976

Studies on metrizamide-protein interactions.

1. The apparent density of catalase after isopycnic centrifugation in metrizamide gradients is dependent on the metrizamide concentration into which the enzyme is dissolved at the beginning of the centrifugation. 2. This different behaviour of the enzyme in metrizamide gradients is due to the formation of a metrizamide-protein complex which is more dense than the uncomplexed catalase. 3. A bimodal distribution of the catalase, with additional heavy bands, was only observed in metrizamide gradients in light water, where rather high metrizamide concentrations are needed even for a banding of the uncomplexed enzyme. 4. The half-life of the metrizamide-protein complex is less than 5 min. This was shown by spectroscopical measurements and band sedimentation analysis in an analytical ultracentrifuge.

Binding Sites↗
PubMed1975

Aminopeptidases of Physarum polycephalum. Activity, isoenzyme pattern, and synthesis during differentiation.

In extracts from both growing and differentiating (spherulating) plasmodia of the true slime mold Physarum polycephalum, high aminopeptidase activities were found. The specificity of the aminopeptidases changed during differentiation with a higher relative activity towards hydrophobic NH2-terminal amino acids. This change in specificity was found to be the result of a shift in the isoenzyme spectrum during differentiation as was tested by isoelectric focusing in sucrose gradients. Three different classes of isoenzymes were found: one band which was present in both growing and differentiating cultures; two bands which were found only in growing cultures; and four bands which were detectable only in differentiating plasmodia. If cycloheximide was applied during the induction of differentiation, only one band, the one present in both types of plasmodia, was found in the isoelectric focusing. Density labeling experiments using deuterated amino acids revealed that the bands which are present in differentiated plasmodia only are synthesized de novo during this differentiation.

Aminopeptidases↗
PubMed1975

Activity, isoenzyme pattern, and synthesis of UDPglucose 4-epimerase during differtiation of Physarium polycephalum.

1. The specific activity of UDPglucose 4-epimerase (EC 5.1.3.2) increases by about 50% during the first 24 h of starvation-induced differentiation (spherulation) of Physarum polycephalum. 2. At all stages during differentiation, the enzyme activity is very sensitive to actinomycin-C and cycloheximide, inhibitors of transcription and translation, with a half life against cycloheximide of about 20 min (if added 12 h after the induction of differentiation). 3. The isoenzyme pattern, as revealed by isoelectric focusing in sucrose gradients, does not change during spherulation. One main band with a pI of 6.7, with a shoulder (pI 7.6) and a minor band (pI 6.0) was observed in extracts both from growing and differentiating cultures. 4. Density labelling experiments using deuterated amino acids with subsequent analysis by equilibrium density gradient sedimentation in 15-35% (w/w) metrizamide gradients revealed a rather slow rate of enzyme synthesis, which is in contrast to the observed high sensitivity against actinomycin-C and cycloheximide.

Carbohydrate Epimerases↗
PubMed1975

Induction of alpha-glucosidase and synthesis during the cell cycle of Myxobacter AL-1.

Alpha-Glucosidase of Myxobacter AL-1 was induced by the addition of maltose to a defined medium as the sole carbon source. This induction takes place during lag-phase conditions without concomitant growth; it seems not to be regulated by the mechanism of catabolite repression. Using the method of density labeling with deuterated amino acids and subsequent analysis by equilibrium density gradient centrifugation in metrizamide-2H2O gradients it could be shown that the activity increase of the enzyme during induction is the the result of a de novo synthesis of the enzyme protein. After a short pulse of induction with maltose, alpha-glucosidase exhibited a pattern of variation in enzyme activity during the cell cycle that was similar to the one observed after growth of the cells on maltose for several generations.

Cell Division↗