Multiple lactate dehydrogenase alleles in the LizardAgama stellio

Zusammenfassung Es wurde das gehäufte, geographisch begrenzte Auftreten multipler Allele für LDH-H, das bei den bisher untersuchten Organismen nur selten Varianten zeigt, nachgewiesen. Ebenso gelang die Identifizierung von elektrophoretischen Varianten in Abhängigkeit vom pH.     

Ambiquitous behavior of rabbit liver lactate dehydrogenase

Summary Rabbit liver mitochondrial fraction shows lactate dehydrogenase activity. The enzyme can be released from particles by increasing the pH and the ionic strength of the medium. There is a narrow range of pH (6.8–7.4) and ionic strength (20–50 mM NaCl) in which the solubilization sharply increases. It has been shown that divalent anions (SO ₄ ^2– ) and cations (Mg²⁺, Ca²⁺) are highly effective specific solubilizing agents. NADH (1.5 mM) and ATP (1.0 mM) were effective in solubilizing 50% of the enzyme bound, whereas the same concentrations of the analogs NAD⁺ and ADP had little effect. Cytosolic lactate dehydrogenase bound to the mitochondrial fraction and a saturation of particles by enzyme was observed in all experiments performed. The in vitro binding requires a short period of incubation between the enzyme and particles and the binding is independent of the temperature in the 0–37°C range. Binding was prevented by 0.15 M NaCl. The bound enzyme is approximately 20% less active than the soluble one. The results described give support to the proposal that rabbit liver lactate dehydrogenase has an ambiquitous behavior, like other glycolytic enzymes, which have not a fixed intracellular localization.     

Ambiquitous behavior of rabbit liver lactate dehydrogenase

Rabbit liver mitochondrial fraction shows lactate dehydrogenase activity. The enzyme can be released from particles by increasing the pH and the ionic strength of the medium. There is a narrow range of pH (6.8-7.4) and ionic strength (20-50 mM NaCl) in which the solubilization sharply increases. It has been shown that divalent anions (SO4(2-) and cations (Mg2+, Ca2+) are highly effective specific solubilizing agents. NADH (1.5 mM) and ATP (1.0 mM) were effective in solubilizing 50% of the enzyme bound, whereas the same concentrations of the analogs NAD+ and ADP had little effect. Cytosolic lactate dehydrogenase bound to the mitochondrial fraction and a saturation of particles by enzyme was observed in all experiments performed. The in vitro binding requires a short period of incubation between the enzyme and particles and the binding is independent of the temperature in the 0-37 degrees C range. Binding was prevented by 0.15 M NaCl. The bound enzyme is approximately 20% less active than the soluble one. The results described give support to the proposal that rabbit liver lactate dehydrogenase has an ambiquitous behavior, like other glycolytic enzymes, which have not a fixed intracellular localization.     

On the regulation of lactate dehydrogenase isoenzyme concentrations in mammalian cells

Zusammenfassung Fritz et al.³ haben in Nature New Biol. 230, 119 ein Modell publiziert, mit dem sie die Regulation der intrazellulären LDH-Isoenzym-Konzentration erklären. Die vorliegende Arbeit zeigt, dass die Resultate vonFritz et al. einfacher durch Heterogenität der Zellen des untersuchten Gewebes erklärt werden kann als durch ihr Modell mit non-random association der LDH-Untereinheiten und verschiedenen turnover-Raten der Isoenzyme in derselben Zelle.

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I thank Drs.Ursprung, D. Turner, D. Seybold andH. Eppenberger for helpful discussions. This work was supported by the Swiss National Science Foundation, Project No. 3.247.69.     

Multiple phosphoglucomutase alleles in two species ofMansonia mosquito

Summary Multiple phosphoglucomutase (E.C.2.7.5.1) alleles are found in the mosquitoesMansonia crassipes andM. uniformis. The present study reveals 4Pgm alleles, of whichPgm ^B andPgm ^C are common to both species whilePgm ^A is present only inM. crassipes andPgm ^D only inM. uniformis. The frequencies in both species accord well with Hardy-Weinberg expectations. The most frequent allele is that controlling a phenotype with an intermediate electrophoretic mobility, viz.Pgm ^B inM. crassipes andPgm ^C inM. uniformis.This work is supported in part by a University of Malaya research grant to the senior author.     

Heterogeneity of lactate dehydrogenase in the developing and adultXenopus laevis daud

Zusammenfassung Das Isoenzymmuster der Laktatdehydrogenase (LDH) wurde mittels Agar-Gel- und Stärke-Gel-Elektrophorese untersucht. Unbefruchtete Eier und Entwicklungsstadien vom 2-Zell-Stadium bis zum 15. Tag wurden als Totalextrakte analysiert; vom 15. Tag an wurden einzelne Organe geprüft und bis ins Adultstadium verfolgt. Die Entwicklung der LDH-Muster ist gekennzeichnet durch Zu- und vorübergehende Abnahme der Anzahl Isoenzyme und durch Verlagerungen der Aktivitäts-Intensitäten. Adultorgane weisen 7 Isoenzyme auf mit Stärke-Gel-Elektrophorese und deren 9 mit der Agar-Gel-Methode; dies steht im Gegensatz zu Untersuchungen an den übrigen Vertebraten-Gruppen, die in der Regel ein LDH-Muster von 5 Komponenten aufweisen.

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This paper is dedicated to Prof. Dr.A. Portmann on the occasion of his 70th birthday.     

A testis-specific lactate dehydrogenase in the pipid frog,Hymenochirus boettgeri

Summary Lactate dehydrogenase zymograms of mature testes ofHymenochirus boettgeri show in addition to the five isozymes composed of LDH-A and LDH-B subunits, a second 5-band system which is due to isozymes formed between LDH-A and a third subunit, LDH-C. These testis-specific LDH-C isozymes appear around 6 months after metamorphosis indicating that their expression is correlated with sexual maturity as is generally the case in mammals. This is the first report of a testis-specific LDH isozyme in a lower tetrapod; such isozymes have hitherto only been reported in mammals and in the pigeon.This study was supported by a grant from the Fond National Suisse de la Recherche Scientifique to H.R.K. We thank M. Sateur and F. Bourquin for their technical help.     

Influence of serotonin on the radiation sensitivity of lactate dehydrogenase

Zusammenfassung Die Veränderungen in der Strahlenempfindlichkeit von Milchsäuredehydrogenase durch Serotonin, gebraucht als Serotonin-Kreatinin-Sulfat, wurden spektralphotometrisch untersucht. Die Bestrahlungsdosen variierten zwischen 0–9 · 10⁵ R. Die Serotonin-Konzentrationen variierten zwischen 0–1,23 mM. Die D³⁷-Dosis für eine Serotonin-Konzentration von 246M ist ca. 34mal grösser als für die Kontrollen. Der Schutzeffekt kann durch eine Komplexbildung zwischen Serotonin und den Metallionen, die im Enzym-Molekül vorhanden sind, erklärt werden.     

Multiple phosphoglucomutase alleles in two species of Mansonia mosquito

Multiple phosphoglucomutase (E.C.2.7.5.1) alleles are found in the mosquitoes Mansonia crassipes and M. uniformis. The present study reveals 4 Pgm alleles, of which Pgm(B) and Pgm(C) are common to both species while Pgm(A) is present only in M. crassipes and Pgm(D) only in M uniformis. The frequencies in both species accord well with Hardy-Weinberg expectations. The most frequent allele is that controlling a phenotype with an intermediate electrophoretic mobility, viz Pgm(B) in M. crassipes and Pgm(C) in M. Uniformis.     

Evolution of a retinal specific lactate dehydrogenase isozyme in teleosts

Résumé Un troisième locus génétique indique la présence d'un unique isozyme de déshydrogénase lactique ne fonctionnant que dans les tissus neuraux des Téléostéens, surtout dans la rétine neurale. La fonction de gène ne se manifeste pas dans les ordres de poissons primitifs. Ces résultats suggèrent une différence de métabolisme rétinien entre les Téléostéens et les classes de poissons plus primitifs.     

Kinetic analysis of lactate dehydrogenase using integrated rate equations

The reaction catalyzed by lactate dehydrogenase was analyzed under fully second-order conditions using integrated rate equations. A two-step regression analysis was utilized to fit twenty-one progress curves repeated in sextuplicate to the general mechanism second-order integrated rate equation with additional terms for substrate inhibition. The fitting error was less than one percent. The resulting kinetic constants support a ternary complex mechanism; in no case were constants supporting another mechanism predicted. The inhibition constant for oxamate was also determined.     

Regional distribution of lactate dehydrogenase isoenzymes in adult rat brain.

The highest lactate dehydrogenase (LDH) activity was found in thalamus, statistically significantly less in cerebral and cerebellar cortex and the lowest in pons. LDH1 and LDH4+5 represented 58% and 23% of the total activity in cerebral cortex, 54% and 20% in thalamus, 42% and 4% in cerebellar cortex and 55% and 7% in pons, respectively.