Effects of Amino Acids on Protein Synthesis by Cellular and Subcellular Preparations from Ischaemic Livers

The effects of liver ischaemia on protein synthesis have been studied in tissue slices from ischaemic livers, incubated in vitro. There is a rapid decrease in protein synthesis after the onset of ischaemia, which is more severe in slices than in any cell-free preparation. Liver slices from ischaemic livers do not respond to the presence of a full complement of amino acids with an increase in protein synthesis. The presence of amino acids in the incubation medium does not protect the state of aggregation of the polysomes in the slices from ischaemic livers, as occurs in normal liver slices. Isolated ribosomes, obtained from ischaemic livers and incubated with normal purified factors, show a reduced—but still evident—increase in their protein synthesis in the presence of a full complement of amino acids. This suggests that the decay of cell sap factors also plays a role in the impairment of protein synthesis caused by ischaemia

Synthesis of (E)-4-(1-pyrenyl)-4-hydroxynon-2-enal, a fluorescent probe of the (E)-4-hydroxynon-2-enal with retained biological properties

(E)-9-(1-pyrenyl)-4-hydroxynon-2-enal (FHNE), a fluorescent probe of (E)-4-hydroxynon-2-enal (HNE) is synthesised in seven steps and in 35% overall yield, starting from commercially available 1-pyrencarboxyaldehyde. When incubated with cultured HeLa cells this fluorescent probe penetrates cells and particularly concentrates in the region surrounding the nucleus. As the parent compound, HNE it is able to induce the activation of heat shock factor (HSF) and it is able to induce the binding of HSF to heat shock element (HSE)

Interactions of liver encoplasmic reticulum membranes and polysomes in vitro.

The interactions of various preparations of endoplasmic reticulum membranes and polysomes have been studied by means of a sandwich sucrose gradient that clearly isolates free ribosomes, smooth endoplasmic reticulum (S.E.R.) and rough endoplasmic reticulum (R.E.R.) from the microsomal fraction of rat liver homogenates. Reconstructed rough membranes separate well from the native R.E.R. but occupy the same position along the gradient as the S.E.R. and the rough membranes, stripped of their ribosomes by means of LiCl. Native R.E.R. and S.E.R. do not bind any added labeled polysomes at 0 degree C; previous treatment with LiCl does not modify the behavior of S.E.R. The presence of cell sap during the binding reaction does not increase polysome fixation by stripped-rough membranes but protects in some way the polysomes and preserves all their original functional capacity of amino acid incorporation into protein