Guinea pig liver cytosol has an L-threonine deaminase activity distinct from L-serine deaminase]

Using sodium sulfate precipitation, "Sephadex G200" gel filtration and polyacrylamide gel electrophoresis, a L-threonine desaminase was demonstrated in the Guinea-Pig liver cytosol. This enzyme was separated from the guinea pig liver L-serine desaminase possessing an auxiliary activity on L-threonine substrate described by us in a previous work. The optimals for pH (7,1) and temperature (+ 55 degrees C) and the apparent molecular weight (134,000 + 20,000) were established.     

Human adenosine deaminase and chromosome 20

Summary In patients exhibiting in marrow cells deletion of the long arm of chromosome 20, the specific activities of adenosine deaminase in cells of the peripheral blood are normal. This suggests that the gene for adenosine deaminase is not localized to the distal segment of the long arm of this chromosome.This work was supported by Grants from the National Health and Medical Research Council of Australia and the Anti-Cancer Council of Victoria.     

Cytosine deaminase: Structural modification studies

Summary Structural modification studies have shown that a cysteine, a histidine and possibly an arginine residue are involved in the catalytic process. The enzyme gave a single band on polyacrylamide gel electrophoresis, and the amino acid analysis showed it to contain a high proportion of hydrophobic residues, which was in agreement with the chemical modification results.Acknowledgment. We wish to thank Herts CC for a research assistantship (S.Y.) and SRC for a research fellowship (to M.J.G.)     

Cytosine deaminase: structural modifications studies

Structural modification studies have been shown that a cysteine, a histidine and possibly an arginine residue are involved in the catalytic process. The enzyme gave a single band on polyacrylamide gel electrophoresis, and the amino acid analysis showed it to contain a high proportion of hydrophobic residues, which was in agreement with the chemical modification results.     

AMP deaminase, 5'-nucleotidase and adenosine deaminase in rat myocardial tissue in myocardial infarction and hypothermia

AMP deaminase, 5'-nucleotidase and adenosine deaminase have been estimated in skeletal muscle and myocardial tissue in normal rats and in rats subjected to experimental myocardial infarction or hypothermia. A difference in the enzyme distribution was found between the right and left ventricles in the normal rat. A decrease in the activity of 5'-nucleotidase and an increase in the activity of adenosine deaminase were observed in infarcted myocardial tissue. The activity of all 3 enzymes was found to be depressed in the myocardium in rats subjected to hypothermia. These results are discussed in relation to adenosine production and its beneficial effects.     

Occurrence of sepiapterin deaminase in the silkworm,Bombyx mori

Zusammenfassung Im Seidenspinner (Bombyx mori) wird ein Enzym nachgewiesen und angereichert, welches das gelbe Pigment Sepiapterin zu Xanthopterin-B₂ desaminiert. Ferner wird die Substratspezifität des Enzympräparates abgeklärt.     

Changes in activity levels of AMP deaminase and adenosine deaminase in the Indian apple snail,Pila globosa (Swainson) during starvation and aestivation stress

Summary Activity levels of AMP deaminase and adenosine deaminase have been studied in hepatopancreas, foot and mantle tissues ofPila globosa with reference to starvation and aestivation. The activity levels of both enzymes were decreased in all the tissues of aestivating snails while in starved animals AMP deaminase activity was increased, in contrast to the decreased adenosine deaminase activity.Acknowledgments. K. Srinivasa Moorthy and B. Kasi Reddy are thankful to the Department of Science and Technology, New Delhi for the financial assistance. Reprint requests should be addressed to C.S.C.     

Effect of pyrophosphate and orotidine monophosphate on cytosine deaminase regulatory properties

The maximal velocity of the reaction (Vmax) and the half-saturation constant (K0.5) values of the S. typhimurium cytosine deaminase were altered in the presence of its effectors, pyrophosphate and orotidine monophosphate. From the kinetics of orotidine monophosphate inhibition of cytosine deaminase, it was characterized as a mixed-type noncompetitive inhibitor.     

Effect of pyrophosphate and orotidine monophosphate on cytosine deaminase regulatory properties

Summary The maximal velocity of the reaction (V_max) and the half-saturation constant (K_0.5) values of theS. typhimurium cytosine deaminase were altered in the presence of its effectors, pyrophosphate and orotidine monophosphate. From the kinetics of orotidine monophosphate inhibition of cytosine deaminase, it was characterized as a mixed-type noncompetitive inhibitor.     

Muscle spindles in the rat diaphragm

Zusammenfassung Elektrophysiologische Registrierungen afferenter Impulse des Nervus phrenicus aus dem isolierten Rattenzerchfell wurden durch eine histologische Untersuchung des Zwerchfelles unterbaut. Das Vorkommen von durchschnittlich 3 Muskelspindeln in jeder Zwerchfellhälfte wurde nachgewiesen.     

Histochemical demonstration of differences in AMP deaminase activity in rat skeletal muscle-fibres

The histochemical method for AMP deaminase confirms that rat slow-twitch fibres contain less AMP deaminase activity than fast-twitch fibres. However, the enzyme appears similarly localized in all fibre types.     

Adenosine deaminase activity in peripheral blood cells from SJL/J mice

Summary Adenosine deaminase (ADA) activities were measured in peripheral blood cells of SJL/J mice, and compared with those of C57BL/6J animals. No association was observed between the levels of lymphocyte or erythrocyte ADA and immunologic abnormalities in SJL/J mice nor was evidence obtained to suggest a relationship between ADA activity and tumorigenesis in this strain.This work was supported in part by a University College Faculty Research Grant.     

Occurrence of sepiapterin deaminase in the normal type silkworm,Bombyx mori

Summary Sepiapterin deaminase was prepared from the normal strain of the silkworm, Bombyx mori. After inhibition experiments, this enzyme was found to have the same properties as that isolated from the lemon mutant strain. Several new inhibitors and their K₁ values are described for the deaminase.The authors wish to thank Dr Wm. Gyure, Cape Cod Hospital, Hyannis, Massachusetts, USA, for his help in preparing this report.     

Histochemical demonstration of differences in AMP deaminase activity in rat skeletal muscle-fibres

Summary The histochemical method for AMP deaminase confirms that rat slow-twitch fibres contain less AMP deaminase activity than fast-twitch fibres. However, the enzyme appears similarly localized in all fibre types.This study was supported by NIH grant AM 21617.