Beziehungen zwischen Hexokinaseaktivität und Glykolyse in Rattenleber und Hepatomen

Abstract

Normal and precancerous livers as well as primary and transplanted hepatomas are studied for glycogen content, hexokinase- and glucokinase activity, at the same time measuring glycolysis in the high-speed supernatants of these tissues with different substrates and additives.Experimental results show that:1) normal and precancerous rat livers have low hexokinase activity and low glycolysis, but high glucokinase activity and high glycogen content;2) primary DAB hepatomas. on the contrary, have high hexokinase activity and raised glycolysis as well as low glycokinase activity and low glycogen content;3) transplantable DAB- as well as DENA-hepatomas have high hexokinase activity and high glycolyses. while neither glucokinase activity nor glycogen content have been found;4) when using glucose as substrate and adding exogenous hexokinase. there is a considerable increase in formation of lactic acid in all tissue supernatants investigated;5) if glucose-6-phosphate is used instead of glucose, a considerable increase of glycolysis is noted as well.It is concluded from the results obtained that the hexokinase reaction limits the extent of glycolysis in these tissues.

Regulation by Auxin of Carbohydrate Metabolism Involved in Cell Wall Synthesis by Pea Stem Tissue

“…The activities of all the enzymes that participate in conversion of glucose-6-P to UDP-glucose are high compared with that of hexokinase (Table III), as has been observed in several other systems (5,45,51). The intermediary activities are also very high compared with the flux from glucose to polysaccharides in this tissue, which may readily be calculated as 0.1 to 0.12 ,umole of glucose per min per 100 tissue segments from data given in Table II.…”

Activities of Organ Characteristic Enzymes and Noradrenaline and Glycogen Contents in the Albert Hepatoma of C57BL Mice

“…In this respect we find an essential difference to other hepatomas investigated by us earlier. Some of these malignomas were demonstrated to have organ-characteristic enzymes but this was only found in primary tumors, but never in transplanted hepatomas [6,21,22], This underlines the different properties of the individual malignomas and the neces sity of further biochemical and molecular biological studies for a better characterization of carcinogenic processes.…”

“…The urea being formed during estimation of arginase was determined accord ing to Engel and Engel |9). Glucokinase (EC 2.7.1.2) was assayed as previously described [6] by measuring the reduction of NADP at 340 nm in the supernatant fluid prepared by centrifugation of the homogenate at 105.000 g for 30 min.…”

Modifications Du Métabolisme Glucidique Dans Le Foie en Voie De Cancérisation Par Le Diméthylaminoazobenzène I. Recherches Au Niveau Du Cycle Du Glycogène

“…Cette forte concentration de glycogene contredit les resultats de Sydow (1965Sydow ( , 1966 d'une diminution de la teneur du foie en glycogene par suite de la seule ingestion de DAB. Elle est par contre en parfait accord avec I'augmentation continue de I'activitk de la glycogene-synthetase.…”