Dehydrogenase System Research Articles

Vertical distribution of zooplankton glutamate dehydrogenase in relation to chlorophyll in the vicinity of the Nantucket Shoals

The vertical distributions of chlorophyll, and zooplankton glutamate dehydrogenase (GDH) and respiratory electron transport system (ETS) activities were measured at five stations in the vicinity of the Nantucket Shoals using a submersible pump-profiling system. Distinctly lower zooplankton GDH activities and chlorophyll concentrations were found at a station showing little vertical stratification as compared to the other stations where vertical stratification was more pronounced. Maximum GDH activity was observed at or immediately above the chlorophyll maximum at the stratified stations. Respiration to excretion (O:N) ratios determined from the enzyme data were lowest in or just above the chlorphyll maximum, suggesting proteolytic catabolism at those depths. Both features had previously been observed in the oligotrophic Gulf of Mexico. Ammonium excretion determined from GDH activity was estimated to provide 20 to 40% of the total algal nitrogen requirement.

Clofibrate, clinofibrate投与ラット肝におけるエタノール代謝系への影響

Peroxisomal catalase and hepatic oxygen consumption were monitored non-invasively in perfused rat liver.1) The effects of CPIB on ethanol oxidative metabolism were studied in perfused rat livers. In some of the experiments, S-8527 was compared with CPIB.2) When the rats were fed for two weeks either with CPIB (0.5%) or S-8527 (0.1%), CPIB induced hepatomegaly, but otherwise revealed the similar hypolipidemic effects to S-8527.3) The rate of oxygen consumption in CPIB-treated liver was higher than that of the control group.4) The role of alcohol dehydrogenase system in ethanol metabolism was considered to be of less significance in CPIB-treated liver.5) The catalase heme content was increased approximately up to nine-fold in CPIB-treated liver. This result indicated that H2O2 generation rate in CPIB-treated liver was significantly increased. Catalase H2O2 (compound I) was also monitored by organ surface spectrophotometry.6) Chronic treatment with CPIB caused hepatic peroxisomal and microsomal induction. S-8527 (0.1%), however, affected neither O2 consumption nor H2O2 generation rate.These findings suggest that the hypolipidemic mechanisms of CPIB are not exactly the same as those of S-8527.

Thermodynamic studies of the activation of rabbit muscle lactate dehydrogenase by phosphate.

In an attempt to trace the source of phosphate activation of the enzyme-catalysed pyruvate-lactate interconversion by rabbit muscle lactate dehydrogenase, equilibrium constants were measured to examine the effects of phosphate on interactions pertinent to the enzymic process. Frontal gel-chromatographic studies of the binding of NADH to the enzyme established that the intrinsic association constant is doubled in the presence of 50 mM-phosphate in the buffer (pH 7.4, I0.15). From kinetic studies of the competition between NAD+ and NADH for the coenzyme-binding sites of the enzyme it is concluded that the binding of oxidized nicotinamide nucleotide is also doubled in the presence of 50 mM-phosphate. Competitive-inhibition studies and fluorescence-quenching measurements indicated the lack of a phosphate effect on ternary-complex formation between enzyme-NADH complex and oxamate, a substrate analogue of pyruvate. The equilibrium constant for the interaction between enzyme-NAD+ complex and oxalate, an analogue of lactate, was also shown, by difference spectroscopy, to be insensitive to phosphate concentration. Provided that the effects observed with the substrate analogues mimic those operative in the kinetic situation, the equilibrium constant governing the isomerization of ternary complex is also independent of phosphate concentration. It is concluded that enhanced coenzyme binding is the source of phosphate activation of the rabbit muscle lactate dehydrogenase system.

Testicular steroidogenesis in the camel ( Camelus dromedarius) during the mating and the nonmating seasons

Enzyme reactions in the camel testis involved in androgen synthesis were studied to determine the factors which account for the low testosterone production during the nonmating season (NMS). Testes excised during the NMS were found to have a relatively high activity of the eβ-hydroxysteroid dehydrogenase systems of pregnenolone, 17α-hydroxypregnenolone, and dehydroepiandrosterone, but the 4-ene-17α-hydroxylase and 4-ene-17,20-lyase systems were apparently less active than the 5-ene-17α-hydroxylase and 5-ene-17,20-lyase. On the other hand, testes excised during the mating season (MS) were found to have a relatively high activity of 4-ene-17α-hydroxylase, 4-ene-lyase, and 17β-hydroxysteroid oxidoreductase. The 19-hydroxylation and aromatizing activities for testosterone and androstenedione were not detected in testes excised in either season. It is proposed that during the NMS the predominant route of testosterone biosynthesis is pregnenolone → 17α-hydroxypregnenolone → dehydroepiandrosterone → androst-5-en-3β, 17β-diol → testosterone.

Isosterism and molecular modification in drug design : Tetrazole analogue of GABA : Effects on enzymes of the γ-aminobutyrate system

The tetrazole analogue of GABA (γ-aminobutyric acid) has been tested for activity in the γ-aminobutyric-glutamic transaminase and succinic semialdehyde dehydrogenase system from Pseudomonas fluorescens. This analogue was found without activity as substrate but with a specific inhibitory action on the γ-aminobutyric-glutamic transaminase.

Metabolism of primary bile acids by Clostridium perfringens

C. perfringens degraded chenodeoxycholic acid (CDC) into two major products: 7α-hydroxy-3-oxo-5β-cholanoic acid and 3β,7α-dihydroxy-5β-cholanoic acid, the latter appearing very quickly and the former very slowly in whole cell cultures. Yields of about 60 and 16% were obtained for the respective products. Both products, as substrates in C. perfringens cultures, were quickly transformed back to CDC (about 84%) and 3β,7α-dihydroxy-5β-cholanoic acid (about 16%), whereas 7α-hydroxy-3-oxo-5β-cholanoic acid was formed slowly (4–5 days). In contrast to CDC, cholic acid was not epimerized at 3α-OH position; however, 7α, 12α-dihydroxy-3-oxo-cholanoic acid was formed slowly. When 7α,12α-dihydroxy-3-oxo cholanoic acid was substrate, rapid quantitative reduction, back to cholic acid then slow oxidation back to the 3-oxo product was observed. Thirty-six strains of C. perfringens (18 from a culture collection and 18 isolated from human feces) were screened for 3α-OH epimerization and oxidation of the primary bile acids. All but three strains epimerized CDC (yields 14–20%), while none epimerized cholic acid. Oxidation at the 3 position varied from 0–30% for CDC and 0–90% for cholic acid. Cell-free preparations of C. perfringens in the presence of NADP produced both 3-oxo and 3β-hydroxyl products with CDC, but only the 3-oxo product with cholic acid; these activities were non-inducible. The authors propose that 3α-OH isomerization takes place early in log phase via a 3α- and 3β-hydroxysteroid dehydrogenase (HSDH) system. Accumulation of 3-oxo product occurs late in stationary phase as the Redox (Eh) value rises above —100 mV.

Electron transport components from methanogenic bacteria: The ferredoxin from [formula omitted] (strain Fusaro)

A ferredoxin has been isolated from the methanogenic organism Methanosarcina barkeri (strain Fusaro). The protein appears to be constituted by two identical subunits of molecular weight approx. 6000 daltons. The UV-visible spectrum of the protein is characterized by two broad absorption peaks centered at 410 and 300 nm and an absorbance ratio A 410 A 300 = 0.8 . The molar extinction coefficients at 410 and 300 nm are 36,500 and 45,625 M −1 cm −1, respectively. The amino acid compsition of M. barkeri ferredoxin shows a preponderance of acidic residues and lacks five amino acids. The protein contains 8 cysteine residues and approx. 7 iron atoms and 7–8 acid-labile sulfide groups per molecule which are indicative of the presence of two iron-sulfur clusters in the molecule. The N-terminal sequence shows a high degree of homology with the sequences of ferredoxins from Clostridium pasteurianum, Desulfovibrio gigas and Desulfovibrio africanus. M. barkeri ferredoxin functions as an electron carrier in the pyruvate dehydrogenase system. Its possible role in a variety of electron transfer reactions is discussed.

Purification of bacterial malate dehydrogenases by selective elution from a triazinyl dye affinity column

A technique of selective elution from affinity adsorbent columns has been devised for the purification of malate dehydrogenase ( L-malate:NAD + oxidoreductase, EC 1.1.1.37) from a number of mesophilic and thermophilic bacteria. It is dependent on the combined action of both NAD + and L-malate, the two reactants in the malate dehydrogenase system. These two reactants individually or NADH or oxaloacetate alone at its equilibrium concentration in the malate dehydrogenase system cannot effect elution of the enzyme. Evidence is presented suggesting that malate dehydrogenase is eluted as a ternary complex with NAD + and L-malate. Using agarose-linked Procion Red HE3B as the affinity adsorbent, the purification method consists of a single step for some malate dehydrogenase species and two easy steps for the other species. It is rapid and efficient, producing malate dehydrogenase homogeneous by several criteria in good yield.

A mutational analysis of the alcohol dehydrogenase system in barley

Evidence that the alcohol dehydrogenase enzymes in barley are specified by two genes, Adh1 and Adh2 whose products (ADH1 and ADH2) associate by dimerization to give three isozyme sets, Set I (ADH1 . ADH1 homodimer), Set II (ADH1. ADH2 heterodimer) and Set III (ADH2. ADH2 homodimer) is presented. Procedures for the induction and recovery of null activity mutants at the Adh1 locus are described. One such mutant, Adh1-M9, when homozygous results in the absence of Set I and Set II isozymes and in a decrease in the rate of induction of alcohol dehydrogenase activity caused by flooding.

Studies on the interactions of Ca2+ and pyruvate in the regulation of rat heart pyruvate dehydrogenase activity. Effects of starvation and diabetes.

1. Previous studies showed that the activation of pyruvate dehydrogenase within intact rat heart mitochondria of pyruvate is much diminished in mitochondria from starved or diabetic animals [see Kerbey, Randle, Cooper, Whitehouse, Pask & Denton (1976) Biochem. J. 154, 327-348]. In the present study, diminished responses to added Ca2+ and ADP were also found in these mitochondria. 2. Starvation or diabetes did not affect the mitochondrial respiratory control ratio of the ATP content. Moreover, starvation and diabetes did not alter the response of the intramitochondrial Ca2+-sensitive enzyme, 2-oxoglutarate dehydrogenase, to changes in the extramitochondrial concentration of Ca2+ and 2-oxoglutarate, thus indicating that there were no appreciable changes in the distribution of Ca2+ and H+ across the mitochondrial inner membrane. 3. Pyruvate, Ca2+ and ADP were found to have synergistic effects on pyruvate dehydrogenase activity, particularly in mitochondria from starved and diabetic rats. 4. The results suggest that the effects of diabetes and starvation on pyruvate dehydrogenase are not brought about by changes in the distribution of these effectors across the mitochondrial inner membrane or by changes in the intrinsic sensitivity of the kinase or phosphatase of the pyruvate dehydrogenase system to pyruvate, Ca2+ or ADP; rather it is probably that there is an increase in the maximum activity of kinase relative to that of the phosphatase. 6. The results also lend further support to the hypothesis that adrenaline may bring about the activation of pyruvate dehydrogenase in the rat heart by an increase in the intramitochondrial concentration of Ca2+.

The stereospecificity of 3 alpha- and 12 alpha-bile salt hydroxysteroid dehydrogenase systems from four microbial sources.

5 beta-Cholanoates, having a hydroxyl group in the 3 alpha and 3 beta and/or 12 alpha and 12 beta configurations, were tested as substrates for two preparation of 3 alpha-hydroxysteroid dehydrogenase (HSDH) and two preparations of 12 alpha-HSDH. When the 3-OH group was in the alpha configuration, both 3 alpha-HSDH preparations reacted, but when it was in the beta configuration, neither 3 alpha-HSDH preparations reacted. This also held true for the 12 alpha-HSDH preparations.

Spectrophotometric and fluorimetric enzymatic determination of serum creatine kinase mb isoenzyme by using immuno-inhibition

Two fully enzymatic methods, colorimetric and fluorimetric, are reported for the determination of creatine kinase (EC 2.7.3.2) MB isoenzyme after immune-inhibition with the use of goat anti-human CK-M IgG antibodies. The residual creatine kinase activity is assayed by using hexokinase and glucose-6-phosphate dehydrogenase systems; the resulting NADPH is determined spectrophotometrically by reaction with p-iodonitro-tetrazolium violet in the presence of diaphorase as an intermediate electron carrier, or fluorimetrically by coupling the NADPH with resazurin/diaphorase to form resorufin. Both assays take only 12 min and require only 100 or 25μl of serum. The calibration plots of enzyme activities are linear up to 580 and 435 U l -1 of CK-MB in serum for the spectrophotometric and fluorimetric assays, respectively, the coefficients of variation being 2.3% and 4.6%, and the recovery values 103% and 100% respectively. The results correlate very well with those obtained by the Helena electrophoresis—fluoridensitometric methods. As little as 4 U l -1 and 2 U l -1 CK-MB could be measured reproducibly.

Ethanol metabolism in guinea pig: Ethanol oxidation and its effect on [formula omitted] ratios, oxygen consumption, and ketogenesis in isolated hepatocytes of fed and fasted animals

Ethanol metabolism was studied in isolated hepatocytes of fed and fasted guinea pigs. Alcohol dehydrogenase (EC 1.1.1.1) activities of fed or fasted liver cells were 2.04 and 1.88 μmol/g cells/min, respectively. Under a variety of in vitro conditions, alcohol dehydrogenase operates in fed hepatocytes at 34–74% and in fasted liver cells at 23–61% of its maximum velocity, respectively. Hepatocytes of fed animals, incubated in Krebs-Ringer bicarbonate buffer, oxidized ethanol at an average rate of 0.69 μmol/g wet weight cells/min, whereas cells of 48-h fasted animals consumed only 0.44 μmol/g/min under identical conditions. Various substrates and metabolites of intermediary metabolism significantly enhanced ethanol oxidation in fed liver cells. Maximum stimulatory effects were achieved with alanine (+138%) and pyruvate (+102%), followed in decreasing order by propionate, lactate, fructose, dihydroxyacetone, and galactose. In contrast to substrate couples such as lactate/pyruvate and glycerol/dihydroxyacetone, sorbitol with or without fructose significantly inhibited ethanol oxidation. The addition of hydrogen shuttle components such as malate, aspartate, or glutamate to fasted hepatocytes resulted in significantly higher stimulation of ethanol uptake than in fed hepatocytes. Also, the degree of inhibition of shuttle activity by n-butylmalonate was more pronounced in fasted liver cells (77% inhibition) than in fed cells (59% inhibition). These data as well as oxygen kinetic studies in intact guinea pig hepatocytes utilizing uncouplers (carbonyl cyanide- p-trifluoromethoxyphenylhydrazone, dinitrophenol), electron-transport inhibitors (rotenone, antimycin), and malate-aspartate shuttle inhibitors (aminooxyacetate, n-butylmalonate) strongly suggested that the malate-aspartate shuttle is the predominant hydrogen transport system during ethanol oxidation in guinea pig liver. Comparison of the alcohol dehydrogenase-inhibitors 4-methylpyrazole and pyrazole on ethanol oxidation demonstrated that the alcohol dehydrogenase system is quantitatively the most important alcohol-metabolizing pathway in guinea pig liver. Supporting this conclusion, it was found that the H 2O 2-forming substrate glycolate slightly increased ethanol oxidation in liver cells of control animals (+26%), but prior inhibition of catalase by 3-amino-1,2,4-triazole resulted in a significant increase (+25%) instead of a decrease in alcohol oxidation. This finding does not support a quantitatively important role of peroxidatic oxidation of ethanol by catalase in liver. Cytosolic NAD NADH ratios were greatly shifted toward reduction during ethanol oxidation. These reductive shifts were even more pronounced when cells were incubated in the presence of fatty acids (octanoate, oleate) plus ethanol. Inhibitor studies with 4-methylpyrazole demonstrated that the decrease of the cytosolic NAD NADH ratio during fatty acid oxidation was due to an inhibition of hydrogen transport from cytosol to mitochondria and not the result of transfer of hydrogen, generated by fatty acid oxidation, from mitochondria to cytosol. Lactate plus pyruvate formation was slightly inhibited by ethanol in fed hepatocytes but greatly accelerated in fasted cells; this latter effect was mostly the result of increased lactate formation. Such regulation may represent a hepatic mechanism of alcoholic lactic acidosis as observed in human alcoholics. The ethanol-induced decrease of the mitochondrial NAD NADH ratio was prevented by addition of 4-methylpyrazole. Endogenous ketogenesis was greatly increased (+80%) by ethanol in fed liver cells. This effect of ethanol was blunted in the presence of glucose. Propionate, by competing with fatty acid oxidation, was strongly antiketogenic. This effect was alleviated by ethanol. In 48-h fasted hepatocytes, endogenous ketogenesis was enhanced by 84%. Although ethanol did not further stimulate endogenous ketogenesis under these conditions, alcohol significantly increased ketogenesis in the presence of octanoate or oleate. This stimulatory effect of ethanol was almost completely prevented by 4-methylpyrazole. These findings demonstrate that the syndrome of alcoholic ketoacidosis may be due, at least partially, to the additional stimulation of ketogenesis by or from ethanol during fatty acid oxidation in the fasting state.

Mode of androgen action at male and female calf pituitary level

The microcalorimetric method was used to study the specific reaction between 5α-dihydrotestosterone (5α-DHT), progesterone (P) and testosterone (T) with their receptors in the pituitary of male and female calves, at the age of 8–10 weeks. Experiments for measuring the binding affinity were performed at 37°C. Molar enthalpy changes for 5α-DHT are −92.11 ± 1.26 kJ/mol of 5α-DHT for female and −66.99 ± 0.58 kJ/mol of 5α-DHT for male calves, respectively. For P molar enthalpy changes are −56.94 ± 0.54 kJ/mol of P for female and −63.63 ± 0.54 kJ/mol of P for male calves. If we suppose that the molar enthalpy change or the liberated heat is a measure for the number of binding sites, then the ratio of molar enthalpy change for 5α-DHT: P is near 2:1 in females and 1:1 in males, at 37°C. T binding, either to female or male pituitary, is an endothermic process, molar enthalpy changes are +8.79 ± 0.46 kJ/mol of Tin females and +6.28 ± 0.86 kJ/mol of T in male pituitary. This finding raise the question of the possibility of spontaneous formation of T-receptor complex at calf pituitary level. At pituitary level in male rats, T is mainly converted to 5α-DHT and 5α-androstan-3α,17β-diol, under the influence of Six-reductase and 3α-hydroxysteroid dehydrogenase systems. In comparison, in male calf at pituitary level T is converted mainly to 4-ene-androsten-3,17-dione (574 α 36 pg/mg wt) under the influence of 17β-hydroxysteroid dehydrogenase and futher on to 5α-andostan-3,17-dione (159 ± 23 pg/mg wt). In female calf at pituitary level enzymic systems are more like the one at pituitary level in male rats: T is mainly converted to 5α-DHT (427 ± 51 pg/mg wt) and futher on to 5α-androstan-3α, 17β-diol (242 ± 26 pg/mg wet tissue).

Study of red cell enzyme systems in Tehran and Isfahan Iranians.

Blood samples from Tehran and Isfahan were examined for seven red cell enzyme systems. Polymorphic variations was present for acid phosphatase, phosphoglucomutase locus I, adenylate kinase, 6-phosphogluconate dehydrogenase and phosphohexose isomerase loci controlling red cell enzyme systems. Statistical analysis demonstrated no significant variation between the two Iranian samples. Gene frequencies were compared with the distribution pattern known in other Iranian populations. The lactate dehydrogenase and Malate dehydrogenase systems were monomorphic.

Primary deuterium and tritium isotope effects upon V/K in the liver alcohol dehydrogenase reaction with ethanol.

The primary isotope effect upon V/K when ethanol stereospecifically labeled with deuterium or tritium is oxidized by liver alcohol dehydrogenase has been measured between pH 6 and 9. The deuterium isotope effect was obtained with high reproducibility by the use of two different radioactive tracers, viz. 14C and 3H, to follow the rate of acetaldehyde formation from deuterium-labeled ethanol and normal ethanol, respectively. Synthesis of the necessary labeled compounds is described in this and earlier work referred to. V/K isotope effects for both tritium and deuterium have been measured with three different coenzymes, NAD+, thio-NAD+, and acetyl-NAD+. With NAD+ at pH 7, D(V/K) was 3.0 and T(V/K) was 6.5. With increasing pH, these values decreased to 1.5 and 2.5 at pH 9. The intrinsic isotope effect evaluated by the method of Northrop [Northrop, D.B. (1977) in Isotope Effects on Enzyme-Catalyzed Reactions (Cleland, W. W., O'Leary, M, H., & Northrop, D. B., Eds.) pp 112-152, University Park Press, Baltimore] varies little with pH. It amounts to about 10 with NAD+ and about 5 with the coenzyme analogues. Commitment functions and their dependence upon pH calculated in this connection appear to be in agreement with known kinetic parameters of liver alcohol dehydrogenase. This assay method was also applied in vivo in the rat. Being a noninvasive method because only trace amounts of isotopes are needed, it may yield information about alternative routes of ethanol oxidation in vivo. In naive rats at low concentrations of ethanol, it confirms the discrete role of the non alcohol dehydrogenase systems.

Quantitative requirements for NADPH in the support of aromatization by human placental microsomes

Suitable incubation conditions were developed for reduced pyridine nucleotide protection and regeneration to permit quantitative assessment of the NADPH requirement for steroid aromatization by human placental microsomes. 10 mM dithiothreitol was found to protect NADP(H) from microsomal nucleotide pyrophosphatase and 2 mM nicotinamide mononucleotide was utilized to control nucleotide glycohydrolase activity. Under these assay conditions, the initial rates of aromatization obtained with restricted NADPH levels were critically dependent upon both the amount and the source of exogenous NADPH-regenerating dehydrogenase system. With excess Leuconostoc mesenteroides glucose-6-phosphate dehydrogenase, an apparent Km for NADPH of 0.20 μM was observed for aromatization which is significently below all previous estimates of the NADPH requirement and which is at greatest only one-tenth the Km value for NADPH utilization by NADPH-cytochrome c reductase. These findings suggest a potential regulatory role for both NADPH-generating and NADPH-accepting enzymes in the support of estrogen biosynthesis.

The glutamate dehydrogenase system and the redox state of mitochondrial free nicotinamide adenine dinucleotide in myocardium

FEBS LettersVolume 128, Issue 2 p. 356-360 Full-length articleFree Access The glutamate dehydrogenase system and the redox state of mitochondrial free nicotinamide adenine dinucleotide in myocardium E.Matti Nuutinen, E.Matti Nuutinen Department of Medical Biochemistry, University of Oulu, Kajaanintie 52 A, 90220 Oulu 22, FinlandSearch for more papers by this authorJ.Kalervo Hiltunen, J.Kalervo Hiltunen Department of Medical Biochemistry, University of Oulu, Kajaanintie 52 A, 90220 Oulu 22, FinlandSearch for more papers by this authorIlmo E. Hassinen, Ilmo E. Hassinen Department of Medical Biochemistry, University of Oulu, Kajaanintie 52 A, 90220 Oulu 22, FinlandSearch for more papers by this author E.Matti Nuutinen, E.Matti Nuutinen Department of Medical Biochemistry, University of Oulu, Kajaanintie 52 A, 90220 Oulu 22, FinlandSearch for more papers by this authorJ.Kalervo Hiltunen, J.Kalervo Hiltunen Department of Medical Biochemistry, University of Oulu, Kajaanintie 52 A, 90220 Oulu 22, FinlandSearch for more papers by this authorIlmo E. Hassinen, Ilmo E. Hassinen Department of Medical Biochemistry, University of Oulu, Kajaanintie 52 A, 90220 Oulu 22, FinlandSearch for more papers by this author First published: June 15, 1981 https://doi.org/10.1016/0014-5793(81)80116-0Citations: 28AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL References 1 I.E. Hassinen, K. Hiltunen, Biochim. Biophys. Acta, 408, (1975), 319– 330. 2 L.H. Opie, D. Owen, Biochem. J., 148, (1975), 403– 415. 3 J.K. Hiltunen, I.E. Hassinen, Biochim. Biophys. Acta, 440, (1976), 377– 390. 4 D.H. Williamson, P. Lund, H.A. Krebs, Biochem. J., 103, (1967), 514– 527. 5 K. Nishiki, M. Erecińska, D.F. Wilson, Am. J. Physiol., 234, (1978), C73– C81. 6 D.F. Wilson, M. Stubbs, N. Oshino, M. Erecińska, Biochemistry, 13, (1974), 5305– 5311. 7 O. Langendorff, Pflügers Arch. Ges. Physiol., 61, (1895), 291– 332. 8 H.A. Krebs, K. Henseleit, Hoppe-Seyler's Z. Physiol. Chem., 210, (1932), 33– 36. 9 D.D. Tyler, J.C. Gonze, Methods Enzymol., 10, (1969), 75– 77. 10 H.-J. Hohorst, H.U. Bergmeyer Methods of Enzymatic Analysis (1963), Academic Press New York 266– 270. 11 T. Bücher, R. Czok, W. Lamprecht, E. Latzko, H.-U. Bergmeyer Methods of Enzymatic Analysis (1963), Academic Press New York 253– 259. 12 R.G. Narins, J.V. Passonneau, H.-U. Bergmeyer Methoden der Enzymatischen Analyse (1970), Verlag Chemie Weinheim 1540– 1542. 13 E. Bernt, H.-U. Begmeyer, H.-U. Bergmeyer Methoden der Enzymatischen Analyse (1970), Verlag Chemie Weinheim 1659– 1664. 14 E. Kun, E.B. Kearney, H.-U. Bergmeyer Methoden der Enzymatischen Analyse (1970), Verlag Chemie Weinheim 1748– 1752. 15 J.K. Hiltunen, V.P. Jauhonen, M.J. Savolainen, I.E. Hassinen, Biochem. J., 170, (1978), 235– 240. 16 P. Borst, Biochim. Biophys. Acta, 57, (1962), 256– 269. 17 T. Takala, J.K. Hiltunen, I.E. Hassinen, Biochem. J., 192, (1980), 285– 295. 18 V. Kinnula, I. Hassinen, Acta Physiol. Scand., 99, (1977), 462– 466. 19 I. Hassinen, B. Chance, Biochem. Biophys. Res. Commun., 31, (1968), 895– 900. 20 T. Bücher, B. Brauser, A. Conza, F. Klein, O. Langguth, H. Siess, Eur. J. Biochem., 27, (1972), 301– 317. 21 T. Bücher, H. Siess, J.M. Tager Use of Isolated Liver Cells and Kidney Tubules in Metabolic Studies (1976), Elsevier/North-Holland Amsterdam, New York 41– 64. 22 N.O. Kaplan, J. Everse, Adv. Enz. Regul., 10, (1972), 323– 336. 23 R. Scholz, R.G. Thurman, J.R. Williamson, B. Chance, J. Biol. Chem., 244, (1969), 2317– 2324. Citing Literature Volume128, Issue2June 15, 1981Pages 356-360 ReferencesRelatedInformation

Erythrocyte isozymes and hemoglobin types in a southern Brazilian population

A total of 710 White and 1070 Black persons living in Porto Alegre, Brazil were tested for the adenylate kinase, adenosine deaminase (ADA), glucose-6-phosphate dehydrogenase (G6PD), phosphogluconate dehydrogenase (PGD) and hemoglobin (Hb) systems. In general the results were those expected in populations of these ethnic groups with some admixture. Two rare phenotypes were found, one involving a “null” ADA allele and another a G6PD non-deficient variant that is being tentatively named Gd(+) “Guaiba”. In the latter system evidence was obtained for the occurrence of somatic selection. Among the Blacks a significant excess of double PGD A / PGD C , Hb A / Hb S heterozygotes were observed. Eight patients with varied forms of immunologic deficiencies showed normal ADA and purine nucleoside phosphorylase levels.

Action pattern of human pancreatic α-amylase on maltoheptaose, a substrate for determining α-amylase in serum

An enzymatic assay for the determination of α-amylase in serum was developed which employed a soluble substrate, maltoheptaose, and a coupled enzymatic indicator reaction consisting of α-glucosidase and the hexokinase—glucose-6-phosphate dehydrogenase system. We used high-performance liquid chromatography (HPLC) to establish the action pattern of maltoheptaose under the test conditions: (A) the action pattern of α-amylase alone, (B) that of the combined action of α-amylase and α-glucosidase. Conducive to this effort was: the availability of pure maltoheptaose and human pancreatic α-amylase; the development of an adequate procedure for sample pretreatment (partition chromatography on a mixed-bed ion exchanger) and of an HPLC system for separation of substrate and reaction products without interference from by-products of the assay (partition chromatography on a cation-exchange column with acetonitrile—water); and the use of a new, very sensitive refractometric detector revealing sugar amounts as low as 40 ng. We derived the following stoichiometric equations: ▪ The standard deviation of the rate coefficients is about 5%.