Some Properties of Potato Tuber UDPGd-fructose-2-glucosyltransferase (E.C. 2.4.1.14) and UDPGd-fructose-6-phosphate-2-glucosyltransferase (E.C. 2.4.1.13)

Sucrose and sucrose 6-phosphate synthetase were isolated from potato tubers, partially purified and their properties studied. The sucrose synthetase showed optimum activity at 45° and was inhibited competitively by ADP and some phenolic glucosides. The Ki′s for these inhibitors were determined. Mg²⁺ was found to activate this enzyme. Activity toward UDP-glucose or ADP-glucose formation was measured. The optimum conditions for sucrose and UDP-glucose formation were found to differ. The specificity for the glucosyl donor and acceptor were determined.

The optimum conditions for sucrose 6-phosphate synthetase activity were studied. This enzyme was not inhibited by either ADP or phenolic glucosides; UDP-glucose was the only glucosyl donor for sucrose 6-phosphate formation.

     

Testicular angiotensin I-converting enzyme (E.C. 3.4.15.1)

In the two mammalian species (i.e., rabbit and rat) in which it has been studied to date, testicular angiotensin I-converting enzyme possesses distinct physicochemical and immunological properties, and a susceptibility to hormonal regulation that makes it a unique isozyme of the converting enzyme ordinarily distributed throughout the body. The testicular isozyme appears to be a lower molecular weight version of the pulmonary enzyme, with similar, although not identical, catalytic properties. The testicular isozyme is under androgenic control and is associated with germinal cells. Although its function has yet to be elaborated, the testicular isozyme provides an excellent model for the study of tissue-specific regulation of carboxypeptidases.     

First determination of the isozyme patterns of phosphoglycerate mutases (E.C.2.7.5.3) and phosphoglycerate kinases (E.C.2.7.2.3) in human tissues.

We present in this paper the first report about identification of several fractions of phosphoglycerate mutase (PGlyM) activity using starch gel electrophoresis and two different buffer systems. A typical muscle form of PGlyM was detected. It is also shown that isozymes of phosphoglycerate kinase (PGK) can be separated through the buffer system used by Spencer et al; (1964) for the phosphogluco mutase.     

Aminolevulinate dehydratase (E.C. 4.2.1.24): Linkage analysis

Summary Linkage data on aminolevulinate dehydratase (ALADH, E.C. 4.2.1.24) and a series of other human genetic markers are presented. One hundred and two families (25 of them being informative) from southwestern Germany were tested. Close linkage (=0.05) between ALADH and the following markers could be excluded: Rh, PGM₁, Fy, ACP1, MNSs, HLA, Bf, GLO, PGM₃, Jk, Pi, PGP, K, GPT. There is some evidence of possible linkage with HPA.     

The determination of the red cell isoenzymes 6-phosphogluconate dehydrogenase (E.C.1.1.1.44) and acid phosphatase (E.C.3.1.3.2) by means of agarosegel thinlayer electrophoresis (author's transl)

Methods for the determination of the red cell isoenzymes 6-PGD and acP by means of agarosegel thinlayer electrophoresis are referred. Using these relatively simple techniques, results can be obtained after at least two hours. The quality of separation in both systems is higher than that obtained after starch gel electrophoresis.     

Human phosphoglycolate phosphatase (PGP) E.C.3.1.3.18: Linkage analysis

Summary Linkage data on phosphoglycolate phosphatase (PGP) E.C.3.1.3.18 and 26 other human genetic markers are presented. One hundred and one families from the southwestern area of Germany were tested. Close linkage between PGP and the following markers could be ruled out: AB0, acP, ADA, GPT, PGM₁, GLO, HLA, and PGM₃. There is some evidence for possible linkage with MNSs, Rh, Gm and EsD. Family segregation data confirm the hypothesis formerly established by Barker and Hopkinson: three common alleles PGP¹, PGP² and PGP³ at an autosomal locus PGP.Supported by the Deutsche ForschungsgemeinschaftSupported by DAAD and Portuguese Inst. for Scientific Research (INIC)     

Aldehyde oxidase isoenzymes (E.C. 1.2.3.1) in potato tubers (Solanum tuberosum)

Two isoenzymes of aldehyde oxidase (E.C. 1.2.3.1 [EC] ) can be separatedfrom potato tubers (Solanum tuberosum) by polyacrylamide gelelectrophoresis. The pH optima of these two isoenzymes werepH 7.5. Both enzymes can oxidize different aldehydes, e.g. crotonaldehyde,Propionaldehyde, acetaldehyde, formaldehyde, glyoxal and benzyl-aldehyde.The isoenzymes could not use xanthine as a substrate. Formaldehydewas oxidized only in the presence of phosphate ions. A substratedependent inhibition of the enzyme activity is possible throughchloral hydrate. PMS, FMN, riboflavine, cytochrome c and O₂ serve as electronacceptors. (Received December 12, 1973; )     

Daten zur Populationsgenetik der Adenosin-Desaminase (E.C. 3.5.4.4) aus Schleswig-Holstein

Zusammenfassung Es wird über die Häufigkeitsverteilung des Isoenzyms Adenosin-Desaminase (ADA) in Schleswig-Holstein unter Berücksichtigung geographischer Räume berichtet. Dabei konnte zwischen dem geographischen Raum Schleswig-Holstein-West und dem Raum Schleswig-Holstein-Ost ein signifikanter Unterschied in der Genfrequenzverteilung festgestellt werden. Die Auswertung von 516 Mutter-Kind-Paaren ergab keine Abweichung von der Erbhypothese. 62 Nabelschnurblute zeigten keine qualitativen und keine erkennbar quantitativen Unterschiede zu Vergleichsbluten im Stärkegelzymogramm.

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Data on population genetics of adenosine deaminase (E.C. 3.5.4.4) in Schleswig-Holstein

Summary There have been reports on the frequency of appearance of the isoenzyme adenosine deaminase in different parts of Schleswig-Holstein (Northern Germany). A significant difference in the distribution of the gene was found between the West and the East of Schleswig-Holstein. Examination of 516 mother-child pairs revealed no deviations from the hereditary hypothesis.

     

Purification and characterization of an endonuclease (E.C. 3.1.30.1) from Streptomyces tendae

A single-strand-specific endonuclease which converted negatively supercoiled DNA to open-circular and linear DNA was purified to homogeneity with Hb-Sepharose 4B, DEAE Trisacryl M, HA-Ultrogel and PBE-94 chromatofocusing from extracts of Streptomyces tendae ATCC 31160. Bio-Gel P-200 chromatography and electrophoresis in SDS-PAGE indicated the native protein was a monomer with a molecular weight of approximately 40-kDa. This enzyme did not hydrolyze double-stranded linear DNA but digested RNA and circular single-strand DNA. Sequence specificity for nicking of negatively supercoiled DNA was not detected.     

Genetic polymorphism of glycerol-3-phosphate dehydrogenase (E.C.: 1.1.1.8)

Summary By means of starchgel electrophoresis several distinct proteins with G-3-PD activity can be detected in Primates. The relative activities of these isoenzymes are found to vary markedly from tissue to tissue. It is presumed that the G-3-PD proteins are dimers composed of two nonidentical polypeptide subunits (chain A and B), which are determined by two separate gene loci (G-3-PD _A and G-3-PD _B). In liver, kidney and skeletal muscle the subunit B is in great excess, while in heart and brain both subunits A and B are present in almost equal proportions. It is concluded, that the various isozyme patterns are the consequence of random combinations of different polypeptide chains. The results obtained so far indicate, that in Primates 2 alleles occur at the G-3-PD _A locus and 5 alleles at the G-3-PD _B locus. Formal notations are given, and a study on population genetics is reported.

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Zusammenfassung Bei den Primaten können mit der Stärkegelelektrophorese verschiedene G-3-PD-aktive Proteine nachgewiesen werden. Die transspezifische Variabilität ist beträchtlich. Für eine formalgenetische Interpretation ist das Modell zu unterlegen: zwie Cistrons G-3-PD _A und G-3-PD _B mit Information für G-3-PD-Polypeptidketten. Homozygote Individuen besitzen 3 Isoenzymbanden, da die beiden Polypeptidketten zu Dimermolekülen frei assoziieren. Heterozygote Individuen für das Cistron G-3-PD _A bzw. G-3-PD _B besitzen jeweils 6 Isoenzymbanden. Bei doppelt heterozygoten Individuen (sowohl für das Cistron G-3-PD _A als auch für G-3-PD _B) sind insgesamt 10 Isoenzymbanden zu erwarten. Unterschiede in den Syntheseraten für A- und B-Polypeptidketten bedingen eine stark ausgeprägte organspezifische Variabilität. In Leber, Niere und skeletmuskel überwiegt die Synthese für B-Ketten, im Herzmuskel und Gehirn werden A- und B-Ketten in annähernd gleicher Menge gebildet. Auf Grund der bisher vorliegenden Ergebnisse ist bei den Primaten mit 2 allelischen Varianten für das Cistron G-3-PD _A und mit 5 allelischen Varianten für das Cistron G-3-PD _B zu rechnen.

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(Director: Prof. Dr. Dr. H. Ritter)

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Supported by the Deutsche Forschungsgemeinschaft.     

Bovine adrenal 3beta-hydroxysteroid dehydrogenase (E.C. 1.1.1. 145)/5-ene-4-ene isomerase (E.C. 5.3.3.1): characterization and its inhibition by isoflavones

The isoflavones daidzein, genistein, biochanin A and formononetin inhibit potently and preferentially the γ-isozymes of mammalian alcohol dehydrogenase (γγ-ADH), the only ADH isozyme that catalyzes the oxidation of 3β-hydroxysteroids. Based on these results, we proposed that these isoflavones might also act on other enzymes involved in 3β-hydroxysteroid metabolism. Recently, we showed that they indeed are potent inhibitors of a bacterial β-hydroxysteroid dehydrogenase (β-HSD). To extend this finding to the mammalian systems, we hereby purified, characterized and studied the effects of isoflavones and structurally related compounds on, a bovine adrenal 3β-hydroxysteroid dehydrogenase (3β-HSD). This enzyme catalyzes the oxidation of 3β-hydroxysteroids but not 3-, 11β- or 17β-hydroxysteroids. The same enzyme also catalyzes 5-ene-4-ene isomerization, converting 5-pregnen 3, 20-dione to progesterone. The K_m values of its dehydrogenase activity determined for a list of 3β-hydroxysteroid substrates are similar (1 to 2 μM) and that of its isomerase activity, determined with 5-pregnen 3, 20-dione as a substrate, is 10 μM. The k_cat value determined for its isomerase activity (18.2 min⁻¹) is also higher than that for its dehydrogenase activity (1.4–2.4 min⁻¹). A survey of more than 30 isoflavones and structurally related compounds revealed that daidzein, genistein, biochanin A and formononetin inhibit both the dehydrogenase and isomerase activity of this enzyme. Inhibition is potent and concentration dependent. IC₅₀ values determined for these compounds range from 0.4 to 11 μM, within the plasma and urine concentration ranges of daidzein and genistein of individuals on vegetarian diet or semi-vegetarian diet. These results suggest that dietary isoflavones may exert their biological effects by inhibiting the action of 3β-HSD, a key enzyme of neurosteroid and/or steroid hormone biosynthesis.     

Population genetics of red cell glyoxalase I (E.C.: 4.4.1.5)

Summary The polymorphism of Glyoxalase I was investigated in a population sample from Southwestern Germany. The frequency of the GLO² allele was determined to be 0.427.

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Zusammenfassung Der Polymorphismus der Glyoxalase I wurde an einer Bevölkerungsstichprobe aus Südwestdeutschland untersucht. Die Genhäufigkeit für GLO¹ beträgt 0,427.

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Supported by the Deutsche Forschungsgemeinschaft.