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K Schaller

Publications and source records attributed to K Schaller.

At least 55 records · Page 3Linked to original sources
PubMed1981

Structural and functional properties of colicin M.

Colicin M of Escherichia coli Cl139 was isolated in pure form. It consisted of a single polypeptide with a molecular weight of 27,000 +/- 2,000. Colicin M lysed sensitive cells of E. coli but had to act continuously up to the point when lysis commenced (after 20 min). Colicin M was largely resistant to hydrolysis by trypsin except when adsorbed to cells. Within 4 to 5 min after addition of colicin M, cells could be rescued by trypsin or sodium dodecyl sulfate. Later, colicin M was apparently inaccessible to these inactivating agents. Killing of cells by colicin M required Ca2+ ions. Cells could be rescued with ethylene glycol-bis(beta-aminoethyl ether)-N,N'-tetraacetate (EGTA) immediately before the onset of lysis. Under these conditions, colicin M remained bound to the cells, and it became again sensitive to trypsin. We conclude that under the influence of EGTA colicin M is removed from its site of action and becomes again accessible to trypsin at the cell surface.

Calcium Chloride↗
PubMed1981

Temperature-sensitive, colicin M-tolerant mutant of Escherichia coli.

A mutant sensitive to colicin M at 30 degrees C and tolerant at 42 degrees C to high concentrations of colicin M was isolated from Escherichia coli K-12. A temperature shift from 30 to 42 degrees C rescued all cells up to the time they started to lyse at 30 degrees C (25 min after addition of colicin M). The growth rate at 42 degrees C remained unaffected by colicin M. AT 42 degrees C the cell-bound colicin M was inactivated by trypsin, sodium dodecyl sulfate, and antiserum against colicin M. Ferrichrome competed with colicin M at 42 degrees C only during the initial adsorption to the common receptor protein in the outer membrane. Since cells lysed earlier at 30 degrees C when they had been preincubated with colicin M at 42 degrees C, we conclude that the process leading finally to cell lysis is initiated at 42 degrees C and stops at a later stage of colicin M trypsin, dodecyl sulfate, and antiserum when cells were transferred from 30 to 42 degrees C, we assume that colicin M is translocated from its target site towards the cell surface. The mutation conferring tolerance was mapped close to the rpsL gene.

Chromosome Mapping↗
PubMed1980

Penetration of colicin M into cells of Escherichia coli.

A new class of colicin M-tolerant mutants of Escherichia coli K-12 was isolated. The mutants exhibited an unusually high tolerance in that they were unaffected by colicin titers of 10(6). The tolerance was confined to colicin M. It was mapped at a locus called tolM, which is close to rpsL. The following gene order was determined: aroE, tolM, rpsL, cysG. The tolerance could be caused by a defect in the uptake of colicin M or by a mutation at the site of action. Insensitive tonA and tonB mutants became sensitive to colicin M upon treatment by osmotic shock, whereas the tolM mutants remained insensitive. Trypsin rescue experiments showed that the tonB-dependent uptake of colicin M required energy like the other tonB-related transport processes. When bound to energy-depleted cells, colicin M prevented adsorption of phage T5. The receptor became accessible to the phage when the cells were energized, except in tonB mutants. These data suggest that the function controlled by the tonB gene is required for the translocation of colicin M from its initial binding site at the tonA-coded receptor protein to the target.

Biological Transport, Active↗
PubMed1977

[Dependence of lactate and heart rate in ergometer-, running- and swimming stress and its use for the preparation of individual conditioning programs for patients with myocardial infarct in rehabilitation phase III].

The dependence of the heart rate of 25 patients between 6th and 12th month after myocardial infarction on the lactate deflection during bicycle ergometry was compared with values being measured in physical conditioning in gymnasium and in indoor swimming-bath. There were found congruent statements in all three types of stress. The immediate comparison of patients undergoing rehabilitation who realized a gymnasium and swimming program simultaneously, showed no differences in lactate deflection and heart rate, too. So heart rates of equal level signal the production of equal metabolic training irritations in the three types of stress being tested. Moreover it was to be ascertained that the optimum intensity of the physical conditioning of patients with myocardial infarction is reached with a lactate deflection of 2,5 to 4,0 muMol/1, appropriate to a heart rate of 104 to 120 beats every minute resp. an efficiency of 70% of the submaximum aerobic capacity.

Conditioning, Psychological↗
PubMed1977

[Dependence of lactate on pulse rate, performance and cardiac volume performance quotient in rehabilitated myocardial infarct patients during bicycle ergometry].

All males of the district Cottbus who suffered from an acute myocardial infarction between 1 June 1973 and 30 June 1974 and survived the first rehabilitation phase of a definite myocardial infarction were included in the study. Their arterial lactate level, the oxygen intake, the heart rate and heart size were determined by means of standardized ergometry and radiology. Patients who had performed a rehabilitation training programme showed a higher efficiency and equal values of lactate level and heart rate compared with the patients without training programme. A close correlation also existed between lactate level and heart rate. There was no dependence on the age of the patient or the degree of heart insufficiency. These results allow to conclude that the lactate level can be used for the determination of the training intensity of patients after an acute myocardial infarction.

Aged↗
PubMed1976

Colicin E2 is DNA endonuclease.

Colicin E2 purified by conventional methods contains a tightly bound low-molecular-weight protein, as has been found with purified colicin E3 [Jakes,N.&Zinder,N.D.(1974) Proc. Natl. Acad. Sci. USA 71, 3380-3384]. Such E2 preparations do not cause DNA cleavage in vitro. After separation from the low-molecular-weight protein, colicin E2 retained the original in vivo killing activity, and in addition showed a high activity in vitro in cleaving various DNA molecules, such as a ColE1 hybrid plasmid and DNAs from Escherichia coli, lambda phage, chiX174 phage, and simian virus 40. The low-molecular-weight protein ("E2-immunity protein") specifically prevented this in vitro DNA cleavage reaction, i.e., had an "immunity function." The results demonstrate that colicin E2 itself is a DNA endonuclease and explain the in vivo effects caused by E2 in sensitive cells as well as the mechanism of immunity in E2-colicinogenic cells.

Colicins↗
PubMed1976

Thiamine absorption in the rat. IV. Effects of caffeic acid (3,4-dihydroxycinnamic acid) upon absorption and active transport of thiamine.

The effects upon thiamine absorption in-vitro and in-vivo by caffeic acid (a thiamine antagonist isolated from bracken) was studied, partly using 14C-thiamine. It was again shown that caffeic acid reduced the quantity of thiochrome positive thiamine, dependant upon the concentration ratio caffeic acid/thiamine. Caffeic acid was able to pass across the intestinal wall and to exert its antithiamine effect in the serosal incubation fluid. When caffeic acid was present in the mucosal fluid the amount of thiochrome positive thiamine passed to the serosal side was diminished according to the mucosal caffeic acid concentration. In-vitro studies with 14C-thiamine revealed, however, that thiamine modified and turned into a thiochrome negative form by caffeic acid was absorbed similarly to unaffected thiamine. Active transport in-vitro of thiamine was significantly inhibited by the presence of caffeic acid.

Animals↗
PubMed1975

Thiamine absorption in the rat. ii. intestinal alkaline phosphatase activity and thiamine absorption from rat small intestine in-vitro and in-vivo.

The correlations between intestinal alkaline phosphatase (IAP) activity and thiamine absorption and glucose absorption were studied in the rat. An everted sac in-vitro technique was used in adult rats whereas in-vitro experiments were performed in young rats 10 days old. All incubation experiments were done with 14-C-labeled thiamine. The patterns of IAP activity along the small intestines differed greatly between young and adult rats but were closely paralleled by the distribution of active thiamine transport in adult rats and thiamine absorption in young rats, respectively. When IAP was specifically inhibited in adult rats by L-phenylalanine active thiamine transport in-vitro was abolished. No correlation was found between IAP activity and active transport or glucose in-vitro, nor did inhibition of the enzyme in any way affect glucose transport capacity. It is suggested that the enzyme intestinal alkalinephosphatase is involved in the process of active thiamine absorption.

Age Factors↗