Isolation of fatty acids from the mycelium ofPenicillium stipitatum thom and their effect on ehrlich ascites carcinoma cells

1974 ◽  
Vol 19 (4) ◽  
pp. 301-306 ◽  
Author(s):  
J. Fuska ◽  
I. Kuhr ◽  
V. Koman
1965 ◽  
Vol 43 (7) ◽  
pp. 977-991 ◽  
Author(s):  
P. G. Scholefield

The oxidation of leucine-1-14C to14CO2by Ehrlich ascites carcinoma cells was inhibited on addition of pyruvate and other α-keto acids, a maximum inhibitory effect being attained with 1 mM pyruvate. The only compound, among those tested, which reversed this inhibition was malonate. Oxidation of leucine-2-14C to14CO2occurred at a rate which was 1% of that observed with leucine-1-14C and was sensitive to the presence of fatty acids as well as to pyruvate. Glutamine was a particularly effective inhibitor of leucine oxidation. The inhibition produced by isoleucine was competitive, the KIvalue being 0.13 mM compared with the KMvalue of 0.2 mM. It is suggested that the inhibition by pyruvate is due to a competition between pyruvate and the α-ketoisovaleric acid derived from leucine for the cofactors required for the oxidation of the α-keto acids. In contrast, oxidation of leucine-1-14C by mouse liver slices was increased approximately threefold by pyruvate.


Author(s):  
Shaikh Shohidul Islam ◽  
Md. Rezaul Karim ◽  
A. K. M. Asaduzzaman ◽  
A. H. M. Khurshid Alam ◽  
Zahid Hayat Mahmud ◽  
...  

1965 ◽  
Vol 43 (2) ◽  
pp. 209-224 ◽  
Author(s):  
B. I. Uppin ◽  
P. G. Scholefield

Studies have been made of the effects of metabolic inhibitors on the oxidation and incorporation of radioactivity into nucleotides of glucose labelled in the 1, 2, and 6 positions. The results indicate that in Ehrlich ascites carcinoma cells the predominant oxidative pathway is the hexosemonophosphate shunt. Investigation of the time courses of oxidation of the labelled glucose molecules confirms this conclusion. The pattern of incorporation of radioactivity initially suggests that nucleotide ribose is not formed via this pathway. However, it is shown that the coupling of an active transketolase system with the other enzymes of the hexosemonophosphate shunt provides a sufficient explanation of all the experimental observations. The conclusion is reached that pentose is formed by oxidation of glucose through the shunt but that the labelling pattern is largely established as the result of the exchange reaction catalyzed by transketolase.


1961 ◽  
Vol 39 (11) ◽  
pp. 1717-1735 ◽  
Author(s):  
P. G. Scholefield

The cumulative entry of amino acids into Ehrlich ascites carcinoma cells is due to the presence of active transport systems, each with its own specific range of substrates. Several amino acids and amino acid analogues may have an affinity for the same transport system and thus may inhibit transport of other amino acids by acting as competitive inhibitors or competitive substrates. Loss of methionine from ascites cells takes place by a diffusion process which obeys Fick's law. Leucine accumulation by ascites cells is small and is increased on addition of certain other amino acids. The increase is not due to inhibition of leucine oxidation as increase in the rate of production of radioactive carbon dioxide from labeled leucine also occurs. Kinetic aspects of these results are discussed.


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