Some comparative studies of two alkaline phosphatases fromAspergillus niger

Summary Alkaline phosphatases (ALP I and ALP II), isolated and purified fromAspergillus niger exhibited broad specificity towards a wide variety of substrates, and consistently ALP II was more active than ALP I. It is possible that the difference in levels of activity of the 2 enzymes may be of physiological importance in the mycelia ofA. niger.     

Continuous optical determination of alkaline phosphatase

Zusammenfassung Ein kontinuierliches optisches Messverfahren für die Bestimmung der alkalischen Phosphatase mitp-Nitrophenyl-phosphat als Substrat wird ausführlich beschrieben. Das Verfahren wird zur Bestimmung der alkalischen Phosphatase in der Rattenniere angewandt.

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This research is a contribution from the Impresa Enzimologia Group of the Italian Consiglio Nazionale delle Ricerche.     

Repressible alkaline phosphotase inAspergillus niger

Summary ALP fromA. niger is a) P_i repressible enzyme; b) stimulated by addition of Zn⁺⁺ to the growth medium, and c) that EDTA inhibits the enzyme reversibly, which could be restored by addition of Zn⁺⁺ and perhaps Mg⁺⁺. This property is in contrast to the enzyme fromN. crassa, which is independent of any metal requirement.     

Phosphoprotein phosphatase activity of bovine intestinal alkaline phosphatase

The phosphoprotein phosphatase activity of a commercial preparation of bovine intestinal alkaline phosphatase (EC 3.1.3.1) was examined using phosvitin and dentine phosphoprotein as substrates. Over 90% and 70% of the phosphorus from dentine phosphoprotein and phosvitin were hydrolyzed in 2 h. The optimum pH of the enzyme for the dephosphorylation of phosvitin and dentine phosphoprotein was nearly 6. No protein phosphatase activity was observed when the alkaline phosphatases from bovine liver and pulp were investigated.     

Formation of trypsin inhibitors during alkaline treatment of proteins

Casein is submitted to a severe alkaline treatment (NaOH 0,2 or 0,5 N, 1 hr., 80 degrees C). The hydrolysis by pancreatic enzymes (trypsin or chymotrypsin) is reduced in vitro and, in the case of the more severe treatment, stopped. After an extended (24 hrs.) trypsin and pronase hydrolysis, it is shown, by affinity chromatography, that peptides, which are not hydrolysable, can bind to trypsin and inactivate this enzyme in vitro.     

Dissociation-constants of metal-ion-complexes with alkaline phosphatase from pig kidney

Summary Using metal-ion buffers it was possible to remove Zn²⁺, Mg²⁺ and Mn²⁺ ions of pig kidney alkaline phosphatase reversibly. The dissociation constants obtained are K_EMg:4·10^–7 M, K_EMn:4·10^–8 M and K_EZn:8·10^–13 M (22°C, pH:9.6, :0.07).Acknowledgement: The authors thank Dr.H. U. Wolf for helpful suggestions and valuable discussion and MissH. Köth for technical assistance.     

Nature of inhibition of rat testicular alkaline phosphatase by isatin

Summary Isatin has been found to inhibit rat testicular alkaline phosphatase (EC 3.1.3.1). That the inhibition is non-competitive as well as non-allosteric is evident from a) the hyperbolic curve relating inhibition as a function of inhibitor concentration; b) the small change in enthalpy, free energy and entropy; c) the number of isatin molecules associating with 1 molecule of the enzyme (n=1.29); and, d) the decrease in the values of both K_m and V_max in the presence of isatin.     

A new concept of the alkaline oxidation of uric acid

Zusammenfassung Früher veröffentlichte Arbeiten über die alkalische Oxydation der Harnsäure wurden ergänzt durch eine Untersuchung über die Struktur von Uroxansäure sowie der Zwischenprodukte, die im alkalischen Oxydationsgemisch auftreten. Die Resultate führen zu einer grundlegend neuen Auffassung über den Mechanismus der Abbaureaktion (Schema II). Uroxansäure ist ein Imidazolidon (XIII) und nicht ein offenkettiges Diureid (III); das vonBehrend formulierte Zwischenprodukt II hingegen, dem man bisher in der alkalisch-chemischen sowie auch in der enzymatischen Harnsäureoxydation eine Schlüsselstellung einräumte, muss durch offenkettige Verbindungen ersetzt werden (XIV, XV, X), in denen das zentrale C-Atom auf die frühere Harnsäure-position 4 zurückgeführt werden kann.     

Nature of inhibition of rat testicular alkaline phosphatase by isatin

Isatin has been found to inhibit rat testicular alkaline phosphatase (EC 3.1.3.1). That the inhibition is non-competitive as well as non-allosteric is evident from a) the hyperbolic curve relating inhibition as a function of inhibitor concentration; b) the small change in enthalpy, free energy and entropy; c) the number of isatin molecules associating with 1 molecule of the enzyme (n=1.29); and, d) the decrease in the values of both Km and Vmax in the presence of isatin.     

Possible role of intestinal alkaline phosphatase activity in thiamine transport

Summary Thiamine deficiency caused a marked decrease of intestinal alkaline phosphatase (al-Pase) activity, but had no effect on the Ca⁺⁺-ATPase activity and Ca⁺⁺-absorption in rats. The al-Pase activity was significantly decreased 1 h after oral administration of ethanol at 0.5 and 2.5 g/kg. In contrast, Mg⁺⁺-, Ca⁺⁺- and (Na⁺+K⁺)-ATPase activities did not change after the administration of ethanol. These findings show that the al-Pase activity, unlike the Ca⁺⁺-ATPase activity, is not related to Ca⁺⁺-absorption. A possible role of al-Pase activity in the active transport of thiamine in the intestine was discussed.     

Dissociation-constants of metat-ion-complexes with alkaline phosphatase from pig kidney.

Using metal-ion buffers it was possible to remove Zn2+, Mg2+ and Mn2+ ions of pig kidney alkaline phosphatase reversibly. The dissociation constants obtained are KEMg: 4 X 10(-7) M, KEMn: 4 X 10(-8) M and KEZn: 8 X 10(-13) M (22 degrees C, pH: 9.6, mu: 0.07).     

Potentiation of angiotensin action on smooth muscle by alkaline pH

Zusammenfassung Die Potenzierung der Wirkung von Angiotensin auf das isolierte Meerschweinchen-Ileum wird bewiesen, wenn das Tyrodebad auf pH 9,3 alkalinisiert ist. Diese Potenzierung wird mit Bradykinin, Oxytocin, 5-Hydroxytryptamin und Histamin nicht beobachtet.     

Partial purification and some characteristics of hamster molar alkaline phosphatase

Summary A rapid 3-step method is given to purify partially hamster molar alkaline phosphatase. Molecular weight was 50,200 and isoelectric point 3.7. The alkaline phosphatases in the mesenchymal and ectodermal parts of the tooth are probably identical.