The purification and properties of arginine phosphokinase

Abstract

FORMATION OF AMMONIA FROM GLUTAMINE 143 presence of IMP and CP resulted in about 97 % inhibition of production of ammonia. This result would be expected if the enzyme responsible were the brain glutaminase described by Krebs (1935). With inorganic phosphate (5 or 10 tmoles/ml.) replacing the IMP and CP in the system, addition of glutamic acid (4 /Lmoles/ml.) was accompanied by a very marked decrease in production of ammonia. Greenstein & Leuthardt (1948) found that bicarbonate buffer did not activate glutaminase. Further evidence for this has been found in the low blank values. They measured the stimulatory effect of various ions on glutaminase, and some organic derivatives of phosphate and arsenate. The present study has included more multivalent ions, since Greenstein & Leuthardt (1948) had shown that univalent ions were poor stimulators ofthe reaction. It was concluded that, in general, as the ionic charge increased so did the effectiveness in stimulating production of ammonia (Table 5). The effect obtained by Weil-Malherbe (1953) can be readily explained on the basis of an anion activation of brain glutaminase by phosphate formed by hydrolysis during the incubation, or by phosphate and sulphate added initially in these solutions. SUMMARY 1. The formation of ammonia from glutamine by rat-brain particles in the presence of inosine triphosphate, or inosinic acid and creatine phosphate, is explained by the presence of low concentrations of phosphate and sulphate which activate the glutaminase present. 2. The reaction is 97 % inhibited by the addition of L-glutamic acid. 3. The effect of various other ions on the reaction was studied. The results indicated that, as the ionic charge increases, so does the efficacy in stimulating production of ammonia. 4. The synthesis of adenosine 5'-monophosphate from inosinic acid does not occur in this system under these conditions.

Age-Related Activity Changes in Arginine Phosphokinase in the House Fly, Musca Domestica L

“…Enzyme assay.-APK activity was determined by the acid hydrolysis of the phosphoarginine formed and the estimation of the inorganic phosphate released by modification of the methods originally described by Morrison, Griffiths, and Ennor (1957). Final concentrations in the standard reaction mixture were 0.06 M N-ethylmorpholine (pH 8.4), lOmM L-arginine, 10 mM ATP, and 10 mM MgSO 4 in a total volume of 1 ml.…”

Evidence of a triosephosphate isomerase non-catalytic function critical to behavior and longevity

“…Arginine (Acros Organics) and phospho-arginine (P-arg) standards were detected at 205 nm, and all samples were measured in triplicate (Celotto et al, 2011). Phospho-arginine standards were generated as previously described (Morrison et al, 1957). Peak analysis was performed using EZStart 7.3 software (Shimadzu), and P-arg levels were normalized to total arginine and compared across genotypes.…”

L'ATP : L‐arginine phosphotransférase de poids moléculaire élevé

“…Les courbes de variation de la vitesse initiale de la reaction directe en fonction des concentrations de l'un des substrats, Q diverses concentrations maintenues fixes du second substrat, ont des pentes ind6-pendantes de la concentration de ce dernier (Fig.6). Ce fait suggkre l'absence d'effet cooperatif entre les substrats [34], tout comme dans le cas de l'argininc phosphotransftkase de Jasus verrauxi [35,36] et contrairement B ce qui a bt6 observe par Virden et coll. [3].…”