Sul meccanismo della eptoformazione non ossidativa nel muscolo scheletrico

Summary F-1,6-P has been shown to increase the rate of non-oxydative heptoformation from glucose-6-phosphate and fructose-6-phosphate in enzymatic preparations of rat skeletal muscle. The mechanism of this increase — probably due to triose-phosphate, formed by aldolase action on F-1,6-P — is discussed.     

Coupling of fructose-1,6-P2 to aminated agarose by Schiff base reduction. Affinity chromatography of yeast aldolase

Summary Fructose-1,6-P₂ was immobilized by sodium borohydride reduction of the Schiff base formed with aminated agarose (AH-Sepharose 4B^®). The coupling occurs with high yield (25 moles immobilized fructose-1,6-P₂ per ml packed gel) at neutral pH and room temperature. Schiff base reduction thus provides a convenient and mild coupling procedure for sugar phosphates preserving their labile phospho ester bonds. As exemplified by a new isolation procedure for fructose-1,6-P₂ aldolase from yeast, sugar phosphates insolubilized in this manner may be used for affinity chromatography of the corresponding enzymes, provided that contaminating unspecific phosphatases are removed in a preceding fractionation step.This work was supported by the Swiss National Science Foundation, grant No. 3.620-0.75. A preliminary account has been presented at the 10th Int. Congress of Biochemistry, Hamburg, 1976, Abstracts. p. 194.Acknowledgment. The excellent technical assistance of Alice Gasser is gratefully acknowledged     

Coupling of fructose-1,6-P2 to aminated agarose by Schiff base reduction. Affinity chromatography of yeast aldolase.

Fructose-1,6-P2 was immobilized by sodium borohydride reduction of the Schiff base formed with aminated agarose (AH-Sepharose 4B). The coupling occurs with high yield (25 mumoles immobilized fructose-1,6-P2 per ml packed gel) at neutral pH and room temperature. Schiff base reduction thus provides a convenient and mild coupling prodecure for sugar phosphates preserving their labile phospho ester bonds. As exemplified by a new isolation procedure for fructose-1,6-P2 aldolase from yeast, sugar phosphates insolubilized in this manner may be used for affinity chromatography of the corresponding enzymes, provided that contaminating unspecific phosphatases are removed in a preceding fractionation step.     

Oligo-1,6-glucosidase and neopullulanase enzyme subfamilies from the alpha-amylase family defined by the fifth conserved sequence region

The α-amylase enzyme family is the largest family of glycoside hydrolases. It contains almost 30 different enzyme specificities covering hydrolases, transferases and isomerases. Some of the enzyme specificities from the family are closely related, others less so. This study, based on the analysis of 79 amino acid sequences, postulates two subfamilies in the framework of the α-amylase family: the oligo-1,6-glucosidase subfamily and the neopullulanase subfamily. The specific sequence in the fifth conserved sequence region of the family served as the basis for defining the subfamilies: QpDln for the oligo-1,6-glucosidase subfamily and MPKln for the neopullulanase subfamily. This conserved sequence region is proposed to be the selection marker that enables one to distinguish between the two subfamilies. The 'intermediary' sequence MPDLN can be characteristic of the so-called intermediary group with a mixed enzyme specificity of α-amylase, cyclomaltodextrinase and neopullulanase. The evolutionary trees clearly supported the proposed definition of the two subfamilies. Received 12 July 2002; received after revision 28 August 2002; accepted 24 September 2002 RID="*" ID="*"Corresponding author.     

Inhibition of liver fructose 1,6-bisphosphatase activity by Zn2+: Reversal by imidazole pyruvate

Summary Imidazole pyruvate was found to be a very potent natural chelating agent in reversing the inhibition of liver fructose 1,6-bisphosphatase activity by Zn²⁺. This metabolite may play a physiological role in gluconeogenesis.This work was supported by grant RR-8006 from the General Research Branch, Division of Research Resources, NIH, USA.     

Demonstration of fructose 1,6-bisphosphatase in human term placenta

Summary A proteolysed form of fructose 1,6-bisphosphatase (Fru-P₂ase) has been detected and characterized in human term placenta. The extract was found to contain very low levels of activity with an alkaline pH optimum. Western blotting demonstrated a polypeptide of Mr 26,000, instead of the subunit of Mr 36,000 observed in native mammalian Fru-P₂ases.     

The specificity of reactions of polycyclic aromatics II. Polarographic reductions

Zusammenfassung Die polarographische Reduktion polyzyklischer are matischer Verbindungen kann als 1,2-, 1,4- oder 1,6 Addition erfolgen. Der Verlauf der Reaktionen lässt sic aus der Abnahme der Resonanzenergie ableiten.

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F. T. Wallenberger, Tetrahedron Letters9, 5–9 (1959).     

Fructose-1,6-dephosphatase in the liver of chickens' embryos

Riassunto Una fruttoso-1,6-difosfatasi compare nel tessuto epatico di embrioni di pollo già al 6° giorno di incubazione dell'uovo; in seguito aumenta rapidamente e raggiunge il massimo fra il 14° ed il 16° giorno; quindi tende a diminuire, pur mantenendosi sempre superiore a quella del fegato dell'animale adulto. Di pari passo all'aumentare dell'attività dell'enzima si osserva un incremento della concentrazione del glicogeno epatico, che cade però bruscamente all'atto della schiusa.     

Altered microviscosity of in vivo lipid-manipulated membranes inTetrahymena pyriformis: A fluorescence study

Summary By determination using fluorescence polarization measurements with 1,6-diphenyl 1,3,5-hexatriene, ergosterolreplaced pellicle and microsome membranes ofTetrahymena cells become less fluid, whereas those membranes from chimyl alcohol-fed cells are more fluid, when compared with the control native membranes.Acknowledgments. We wish to express thanks to Central Scientific Commerce, Inc., Tokyo for permission to use an Elscint Microviscosimeter MV-Ia. This work was in part supported by grant from the Ministry of Education.     

Inhibition of liver fructose 1,6-bisphosphatase activity by Zn2+: reversal by imidazole pyruvate.

Imidazole pyruvate was found to be a very potent natural chelating agent in reversing the inhibition of liver fructose 1,6-bisphosphatase activity by Zn2+. This metabolite may play a physiological role in gluconeogenesis.     

Proton and potassium fluxes in rat red blood cells incubated with sugar phosphates

Fructose-1,6-diphosphate counteracts potassium ejection and proton uptake induced in rat red blood cells by valinomycin and an uncoupler. The effect on potassium ejection is reduced in the presence of ouabain and divalent cations.     

On dicentric aberration yields in 50-MeV proton-irradiated human peripheral lymphocytes

Zusammenfassung Zur biologischen Dosimetrie wird eine Analyse für die Dizentiks-Ausbeute in Lymphozyten bei in vitro Bestrahlung aus peripherem Menschenblut mit 50-MeV-Protonen durchgeführt. Zur Approximation der experimentellen Befunde erweist sich eine Regressionskurve, entsprechend der GleichungY=(12,6±1,6)×10^–5×D ^{(1,36±0.027)} als vorteilhaft.     

Proton and potassium fluxes in rat red blood cells incubated with sugar phosphates

Summary Fructose-1,6-diphosphate counteracts potassium ejection and proton uptake induced in rat red blood cells by valinomycin and an uncoupler. The effect on potassium ejection is reduced in the presence of ouabain and divalent cations.     

Incorporation of adenine-4,6-C14 into nucleic acids

Zusammenfassung Der Umbau von 4,6-C¹⁴-Adenin in Ribo- und Desoxyribonukleinsäure wurde im Gewebe von jungen Mäusen vom Stamm Webster 17 h nach intraperitonealer Injektion von markiertem Purin analysiert. Das Verhältnis der spezifischen Aktivität von RNA zu DNA variiert von 1,1 bis 1,6 für sämtliche Gewebe, ausgenommen Leber, wo ein Verhältnis von 6,4 gefunden wurde.

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Fellow of The National Foundation for Infantile Paralysis.     

A contribution on the effect of noradrenaline on heat production in mice

Zusammenfassung Bei ausgewachsenen Mäusen wurde nach i.p. Noradrenalininjektion die Steigerung der O₂-Aufnahme über den Grundumsatz in der Thermoneutralzone verfolgt. Nach einer Dosis von 1,6 mg/kg wurde ein bedeutender Unterschied (p < 0,05) der O₂-Aufnahmesteigerung zwischen der Gruppe normaler (155%) und normaler, auf 17°C adaptierter Mäuse (165%) und der Gruppe haarloser Mäuse (195%) festgestellt.     

Heterogeneity of erythrocyte catalase: Variability of the isoelectric point

Zusammenfassung Mittels isoelektrischer Fokussierung wurde der IEP von nativer Erythrocytenkatalase bestimmt (Mensch pH 6,5; Pferd pH 7,3). Die im Verlauf der Reinigung auftretende Konformationsänderung ist von einer Verschiebung des IEP nach der sauren Seite begleitet (Mensch pH —1,3; Pferd lpH –1,6).     

Fructose-1,6-diphosphate reduces acute ECG changes due to doxorubicin in isolated rat heart

Doxorubicin (DXR) (0.17 x 10(-4) M) induces an acute cardiotoxicity in isolated rat heart; there is a progressive widening of the S alpha T segment, with a decrease in force derivatives and in the coronary flow. Concurrent perfusion with fructose-1,6-diphosphate (FDP) (10(-5)-10(-4) M) dose-dependently reduces the S alpha T enlargement but fails to affect the reduction in force derivatives and coronary flow. The target of cardiac protection by FDP might be the ionic mechanisms underlying the action potential configuration.     

Demonstration of fructose 1,6-bisphosphatase in human term placenta.

A proteolysed form of fructose 1,6-bisphosphatase (Fru-P2ase) has been detected and characterized in human term placenta. The extract was found to contain very low levels of activity with an alkaline pH optimum. Western blotting demonstrated a polypeptide of Mr 26,000, instead of the subunit of Mr 36,000 observed in native mammalian Fru-P2ases.     

Phosphatases ofMycobacterium 607

Zusammenfassung Die Phosphatase(n)-Aktivität der zellfreien Extrakte vonMycobacterium 607 wurde untersucht und Pyrophosphat, ATP, ADP und Fructose-1,6-diphosphat hydrolisiert. Eigene Eigenschaften der Phosphatasen wurden studiert. Auch wurde nachgewiesen, dass die Hydrolyse von ATP und ADP durch mindestens zwei verschiedene Enzyme hervorzurufen ist.

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Supported in part by funds from Indian Council of Medical Research, New Delhi and Grant No. E-3427, National Institute of Allergy and Infectious Diseases U.S.P.H.S. Thanks are due to Dr.R. Viswanathan for his interest in this work.     

Immobilization of chicken liver fructose 1,6-bisphosphatase on CNBr-activated Sepharose

Summary Chicken liver fructose 1,6-bisphosphatase is readily immobilized on CNBr-activated Sepharose. The immobilization alters some enzymatic properties. They include broader pH activity curve, loss of activation by K⁺ or NH ₄ ⁺ , increased resistance to inactivation by trypsin, decreased sensitivity to AMP inhibition, and loss of cooperative interaction among AMP-binding sites. The immobilized enzyme retains about 38% or 19% of the specific activity of the native enzyme when the activity is measured in the absence or presence of K⁺, resepctively.This work was supported by grant RR-8006 from the General Research Branch, Division of Research Resources, NIH (USA).