Catheptic activity of blood serum in cancer

Libenson, Leon; Jena, Milton; Lynch, Harry J.; Finn, Frances M.

doi:10.1002/1097-0142(195709/10)10:5<1004::aid-cncr2820100520>3.0.co;2-s

Cited by 11 publications

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“…Glutathione is present in all mammalian tissues. Low concentrations of this tripeptide are also present in plasma, either free [ l ] or protein-bound as a mixed disulfide with thiol groups of albumins [2,3]. Two analogs of glutathione, namely, ophthalmic acid [4] (~-y-glutamyl-~-2-arninobutyrylglycine) and norophthalmic acid [5] (L-y-glutamyl-L-alanylglycine) have been discovered in calf lens.…”

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Metabolism of γ‐Glutamyl Amino Acids and Peptides in Mouse Liver and Kidney in vivo

Orłowski

Wilk

1976

European Journal of Biochemistry

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The metabolism in vivo of y-glutamyl amino acids and peptides was studied in the mouse after administration of loading doses of ~-y-glutamyl-2-aminobutyrate and several other y-glutamyl compounds, including glutathione. A great and rapid accumulation of glutamate, glutamine, aspartate and pyrrolidone carboxylate was observed in the kidney. Similarly, after administration of a tracer dose of ~-y-[~~C]glutamyl-~-2-aminobutyrate a rapid incorporation of label into kidney glutamate, glutamine and aspartate was found. These results suggest that both the hydrolytic and ;I-glutamyl transfer reactions catalyzed by y-glutamyl transpeptidase are active in the renal handling of y-glutamyl compounds.Indirect evidence was obtained that ~-y-glutamyl-2-aminobutyrate is partially taken up by the kidney cell in an intact form.In contrast to the kidney, administration of several y-glutamyl derivatives did not cause an increase in liver glutamate, glutamine and pyrrolidone carboxylate. After administration of L-7-glutamyl-2-aminobutyrate only a slight increase in liver aspartate and pyrrolidone carboxylate was observed. Experiments with ~-y-['~C]glutamyl-~-2-aminobutyrate suggest that this derivative is largely first degraded to its component amino acids (probably in the kidney) before entering into the metabolism of the liver cell.7-Glutamyl transpeptidase may function in the metabolism and transport of glutathione and other y-glutamyl compounds in a manner analogous to the function of dipeptidases and disaccharidases in the metabolism and transport of dipeptides and disaccharides respectively. y-Glutamyl amino acids and peptides are derivatives of glutamate in which the y-carboxyl group participates in a peptide bond with an amino acid or peptide. The most commonly occurring representative of this class of compounds is glutathione (L-Yglutamyl-L-cysteinylglycine). Glutathione is present in all mammalian tissues. Low concentrations of this tripeptide are also present in plasma, either free [ l ] or protein-bound as a mixed disulfide with thiol groups of albumins [2,3]. Two analogs of glutathione, namely, ophthalmic acid [4] (~-y-glutamyl-~-2-arninobutyrylglycine) and norophthalmic acid [5] (L-y-glutamyl-L-alanylglycine) have been discovered in calf lens. y-Glutamyl derivatives of a number of amino acids have been also found in brain [6] and human urine [7,8]. ~-Enzjwze.7. y-Glutamyl transpeptidase or (y-g1utamyl)-peptide: amino acid y-glutamyltransferase (EC 2.3.2.2); y-Glutamylcyclotransferase (EC 2.3.2.4); y-Glutamylcysteine synthetase (EC 6.3.2.2); Glutathione synthetase (EC 6.3.2.3); Glutamine synthetase (EC 6.3.1.2). y-Glutamyl amino acids are formed in cico by two separate pathways [9]. In the first glutamate reacts with cysteine or several related amino acids to give the corresponding 7)-glutamyl amino acid. This reaction is catalyzed by y-glutamylcysteine synthetase and is limited by the specificity of this enzyme. It constitutes the first of two steps leading to the synthesis of glutathione or its analogs (Reactions 1 ...

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Metabolism of γ‐Glutamyl Amino Acids and Peptides in Mouse Liver and Kidney in vivo

Orłowski

Wilk

1976

European Journal of Biochemistry

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“…It is not known, however, whether these activities are due to cell damages or if they occur also under normal in vivo conditions. It was cursorily mentioned by Libenson and Jena (1957) that the cell-free tissue fluid within certain transplanted human tumours contained a greater proteolytic activity at pH 4 than the normal subcutaneous tissue fluid distant from the tumour site. Quantitative assays of the peptidase and catheptic activities of the extracellular fluid taken in vivo from various solid mouse tumour transplants (Sylven, unpublished) distinctly indicate that these activities per unit volume are considerably higher than the levels observed in normal lymph and plasma.…”

Section: Previous Data On the Pertinent Enzymic Activitiesmentioning

confidence: 99%