Biomedical subjects

G E Hoffmann

Publications and source records attributed to G E Hoffmann.

39 records · Page 3Linked to original sources

PubMed1979

Pyruvate dehydrogenase and ATP citrate (pro-3S)-lyase activities in adipose tissue and liver of the young lean and the older obese rat.

Pyruvate dehydrogenase and ATP citrate lyase, two lipogenic enzymes, were measured in young, lean and older, obese rats. While no significant differences were observed between the livers of the two groups, both enzymes were greatly reduced in epididymal adipose tissue of older rats. A similar decrease was found in adipose tissue from the perirenal, but not from the interscapular region. Prolonged meal-feeding over a one-year period did not prevent the loss of pyruvate dehydrogenase activity in epididymal fat pads. In short term experiments of two weeks' duration this feeding regimen elevated the activities of both enzymes in adipose tissue of young but not of older rats. It is concluded that the state of activity of adipose tissue pyruvate dehydrogenase and ATP citrate lyase is at least in part responsible for the augmented lipogenesis observed in meal-fed rats and for the reduced lopogenic capacity and insulin sensitivity seen in old obese rats.

ATP Citrate (pro-S)-Lyase↗

PubMed1979

ATP citrate (pro-3S)-lyase in the rat; two-step purification procedure, properties, organ distribution.

A simple two-step procedure is described for the purification of rat liver ATP citrate lyase with an overall yield of upt to 70%. In binding experiments on Blue Sepharose CL-6B (an affinity gel for nucleotide-specific enzymes) it is observed that ATP citrate lyase recognizes ATP and CoA as well as ADP, 3'-AMP, and NADP, but not 5'-AMP, NAD, or adenosine. It is further demonstrated that ATP citrate lyase is activated by various anions including chloride, hydrogen carbonate, and acetate. The highest specific activity of the enzyme is found in adipose tissue of various origins. Activities are also present in the adrenals, in liver, and intestine, in brain, and in lung. No measurable enzyme activity is found in heart, skeletal muscle, and in the kidneys.

ATP Citrate (pro-S)-Lyase↗

PubMed1978

Transfer of C2-units across the mitochondrial membrane. Direct recording of citrate, acetate and acetoacetate production rates.

Methods are described for the direct optical assay of citrate, acetate, and acetoacetate production by isolated, incubated rat liver mitochondria. Each metabolite is converted into acetyl-CoA, using ATP: citrate lyase or acetyl-CoA synthetase or acetoacetyl-CoA synthetase and acetyl-CoA acetyltransferase, respectively. Arylamine acetyltransferase acts as auxiliary enzyme. It was shown that isolated rat liver mitochondria produce citrate, acetate and acetoacetate, and that production rates are stimulated by pyruvate and hexanoate. It was concluded that these three products might contribute to the transport of acetyl units across the mitochondrial membrane and thus serve as precursors in fatty acid synthesis. The rate of acetyl transfer does not seem to be rate-limiting with regard to the overall-process of fatty acid synthesis from carbohydrates.

Acetates↗