Dissociation of urease in acetate buffer of pH 3.5 with retention of the enzymatic activity

Riassunto Le molecole dell'urease (peso molecolare 480,000, coefficiente di sedimentazione 18,6 S) si dividono a metà quando trattate con tampone acetato, 0,1M, pH 3,5. Inizialmente, l'attività enzimatica è 40% di quella al pH 7 (tampone fosfato, 0,34M) e la dissociazione è riversibile. Prolungata esposizione al pH 3,5 causa una lenta denaturazione, con perdita dell'attività e dell'abilità di ricostituirsi.

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This work was supported by grant No. GM 13,900 and by Career Development Award No. 5K3 GM 13,489 (to G. G.) from the National Institutes of Health.     

Calcium as stabilizing factor of the collagen macromolecule

Zusammenfassung Verkalkte Haut junger sowie nor-male Haut junger und alter Tiere wurden mit EDTA behandelt. Das labile Kollagen (löslich in 10 min bei 65 C) steigt in allen Fällen an. Daraus wird geschlossen, dass das Kalzium an der Stabilisierung des Kollagenmakromoleküls beteiligt ist.     

Studies on the activity of phorbol myrystate acetate on the human polymorphonuclear leukocytes.

Phorbol myrystate acetate (PMA) activates nitroblue tetrazolium reduction in human polymorphs. The activation is inhibited by dibutyryl cyclic AMP, theophylline and phenylbutazone, but is not influenced by hydrocortisone in vitro, nor is it inhibited by leukocytes from patients treated with prednisone. Peptide analogues of Tuftsin also had no effect on this stimulatory activity. We conclude that the action of PMA on the nitroblue tetrazolium reduction is mediated through cyclic nucleotides.     

The influence of pH on the sex-related differences in renal organic ion transport.

The stimulating effects of elevated medium pH and androgen on in vitro transport of p-aminohippurate and N-methylnicotinamide (NMN) were additive, although the androgenic effect was pH-dependent only in the case of NMN. The similarity of response of the 2 systems supports the idea of a common passive efflux pathway for organic anions and cations.     

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.     

The effect of ion pair formation on the antimuscarinic activity of methantheline.

The quaternary ammonium compound, methantheline, was found to antagonize acetylcholine induced contractions in isolated guinea pig ileum by a mechanism which did not conform to the criteria for either competitive or non-competitive inhibition. Enhancement of the lipid solubility of methantheline by formation of an ion pair with trichloracetate failed to influence its cholinergic inhibitory activity. The results suggest that in the guinea pig ileum a) an intracellular site of action does not exist for methantheline and b) the membrane receptors for methantheline most likely are located in an aqueous environment.     

Phosphatases VI.1 pH dependence of the organ-specific thermostability of alkaline phosphatases in tissue homogenates

Zusammenfassung Die Hitzeinaktivierung der alkalischen Phosphatase in Darm-, Leber-, Knochen- und Nieren-Homogenaten der Ratte erhöht sich mit steigenden pH-Werten, was für die übliche Bestimmung der Gesamtaktivität des Enzyms bedeutend ist.     

Studies on the activity of phorbol myrystate acetate on the human polymorphonuclear leukocytes

Summary Phorbol myrystate acetate (PMA) activates nitroblue tetrazolium reduction in human polymorphs. The activation is inhibited by dibutyryl cyclic AMP, theophylline and phenylbutazone, but is not influenced by hydrocortisone in vitro, nor is it inhibited by leukocytes from patients treated with prednisone. Peptide analogues of Tuftsin also had no effect on this stimulatory activity. We conclude that the action of PMA on the nitroblue tetrazolium reduction is mediated through cyclic nucleotides.     

The influence of pH on the sex-related differences in renal organic ion transport

Summary The stimulating effects of elevated medium pH and androgen on in vitro transport of p-aminohippurate and N-methylnicotinamide (NMN) were additive, although the androgenic effect was pH-dependent only in the case of NMN. The similarity of response of the 2 systems supports the idea of a common passive efflux pathway for organic anions and cations.Naval Medical Research and Development Command, Research Task No. MS04101.0160. The opinions and assertions contained herein are the private ones of the authors and are not to be construed as official or reflecting the views of the Navy Department or the naval service at large. The experiments reported herein were conducted according to the principles set forth in the Guide for the Care and Use of Laboratory Animals, Institute of Laboratory Animal Resources, National Research Council, DHEW Pub. No. (NIH) 74-23.     

Possible role of intestinal alkaline phosphatase activity in thiamine transport.

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.     

Effect of retinyl acetate feeding on the activity of testicular enzymes in young rats

Summary Feeding of excess vitamin A significantly increased the activity of -galactosidase and -glucuronidase without effecting the activity of acid and alkaline phosphatase in rat testicular homogenates. It is suggested that imbalance of vitamin A affects the normal process of spermatogenesis by altering the activity of lysosomal enzymes.Acknowledgments. The author is grateful to Dr C.M. Singh, I.V.R.I., Izatnagar and Dr L.N. Singh, for providing facilities and encouragement and to Prof. O. Isler, Hoffmann-La Roche, Basel, Switzerland, for the generous supply of retinyl acetate used in this work.     

The effect of ion pair formation on the antimuscarinic activity of methantheline

Summary The quaternary ammonium compound, methantheline, was found to antagonize acetylcholine induced contractions in isolated guinea pig ileum by a mechanism which did not conform to the criteria for either competitive or non-competitive inhibition. Enhancement of the lipid solubility of methantheline by formation of an ion pair with trichloracetate failed to influence its cholinergic inhibitory activity. The results suggest that in the guinea pig ileum a) an intracellular site of action does not exist for methantheline and b) the membrane receptors for methantheline most likely are located in an aqueous environment.