PubMed Health⌕ Search

Biomedical subjects

E R Tustanoff

Publications and source records attributed to E R Tustanoff.

32 records · Page 2Linked to original sources
PubMed1975

Aerobic adaptation in yeast. I. Changes in metabolic intermediates during a step-down anaerobic-aerobic transfer.

Early investigation into the mechanism of mitochondriogenesis in the facultative anaerobe Saccharomyces cerevisiae used anaerobic-aerobic transitions as model systems to study the in vivo assembly of these oxidative organelles. This methodology has become entrenched in the early literature and as a result a definitive study has been undertaken utilizing this protocol (high hexose, complete medium under anaerobic growth transferred to low hexose, minimal medium with aerobic environment) to study the altered distribution of various metabolites during these transitions. Measurement of all the glycolytic, and some tricarboxylic acid intermediates during such a transition has elucidated the following points. On a qualitative basis, the metabolic controls prevalent in these growing cultures are similar to those identified in yeast under less physiological conditions. Also, the effect of anaerobic catabolism, which preconditions enzyme and pool levels in the yeast, is of paramount importance in determining the events subsequent to oxygen challenge. However, this experimental approach has severe limitations and does not lend itself to a clear-cut delineation of the events that occur during the process of mitochondriogenesis.

Adenosine Triphosphate↗
PubMed1975

Aerobic adaptation in yeast. II. Changes in enzyme profiles during a step-down anaerobic-aerobic transfer.

The levels of various enzymes and components of the glycolytic and respiratory pathways of the yeast Saccharomyces cerevisiae have been determined during a step-down, anaerobic-to-aerobic transition. These activities were determined as an adjunct to the respective metabolite data reported in the first paper in this series. It is clear from the data that anaerobic conditions induce an environment conducive to express glycolytic enzyme activities, while manifesting a differential induction/repression effect on oxidative enzymes. An NAD/NADH mediated mechanism is proposed to explain this difference. Of the enzymes assayed only cytochrome c oxidase shows any direct response to oxygen challenge and consequently it is suggested that the assembly of this enzyme is the trigger mechanism and rate-limiting step in aerobic adaptation.

Aerobiosis↗
PubMed1975

Aerobic adaptation in yeast. III. Changes in metabolic intermediates during anaerobic-aerobic transitions in exponentially growing cultures.

The changes in mechanism of control and in the mode of metabolism which yeast cells undergo when an anaerobic-aerobic transition is imposed on them has received much attention. One experimental approach to this type of investigation has been a step-down transition. The data from our experiments (cf. papers I and II of this series) has shown that this model is too complex to arrive at meaningful interpretation. We therefore repeated these measurements of glycolytic and citric acid cycle metabolites in cells growing on either glucose or galactose media and exposed to exponential N2 yields 02 transitions. This type of experiment is designed to examine directly the effect of oxygen challenge. Interpretation of this new data shows that the major metabolic control operating in the two hexose cultures are different and suggests that adenine nucleotide controls glucose cells whereas galactose cell metabolism is controlled by the NAD/NADH balance. This concept is discussed.

Adenosine Triphosphate↗
PubMed1975

Aerobic adaptation in yeast, IV. Alterations in enzyme synthesis during anaerobic-aerobic transitions in exponentially growing cultures.

As a corollary to the metabolite data obtained from yeast cultures undergoing an exponential anaerobic-aerobic phase transition, levels of various glycolytic and citric acid cycle enzyme activities have been monitored in these cells. The relation of the changes in these enzyme activities in cells grown on either glucose or galactose is discussed on light of different metabolic postures these cells demonstrate as a result of their transitions. A general discussion is presented which compares the results obtained in this series of papers from both step-down and exponential transfer experiments and relates these data to control of mitochondriogenesis in yeast.

Aerobiosis↗
PubMed1975

Assembly of complex III into newly developing mitochondrial membranes.

Yeast cells grown anaerobically in 0.02% linoleic acid were transferred to air in the presence of 0.02% elaidic acid. At varying times Arrhenius plots were made of QH2-cytochrome c reductase activities in isolated mitochondria. A transition temperature of 8.2 degrees C at 0.5 h was characteristic of linoleate; at 3 h the transition temperature was increased to 24 degrees C characteristic of elaidate. At early times the enzyme was associated with anaerobic promitochondrial membranes; at later states the newly synthesized enzyme was associated with newly developed elaidate membranes.

Aerobiosis↗
PubMed1966

The effect of metabolic inhibitors on the development of respiration in anaerobically grown yeast.

1. Iodoacetate and fluoride did not prevent the development of respiration in aerobically grown yeast. 2. The effect of dinitrophenol suggested that phosphorylation developed simultaneously with respiration in anaerobically grown yeast, but the effect of oligomycin suggested that the phosphorylation and oxidation were not tightly coupled. 3. Inhibitors of electron transport showed that both the respiratory peak and the subsequent respiration were cyanide-sensitive, but the peak respiration was insensitive to antimycin. 4. Of the inhibitors of protein or RNA synthesis tested, only p-fluorophenylalanine inhibited the development of respiration. The results are not consistent with a new synthesis of mitochondria. 5. 2-Phenylethanol inhibited the development of respiration in anaerobically grown yeast and also yeast growth. Other inhibitors of DNA synthesis had no effect on the development of respiration. 6. The relevance of the results to mitochondrial morphogenesis is discussed.

Amino Acids↗