H.G. Williams-Ashman

Methyl glyoxal bis(guanylhydrazone) as a potent inhibitor of mammalian and yeast S-adenosylmethionine decarboxylases.

Abstract The putrescine-activated S-adenosylmethionine decarboxylases of rat ventral prostate and bakers yeast are strongly inhibited by methyl glyoxal bis(guanylhydrazone), a substance which has been reported to exhibit anti-leukemic actions. Low concentrations of the drug preferentially inhibit the enhancement by putrescine of the decarboxylation of S-adenosylmethionine by the prostate enzyme. The magnesium ion-activated and putrescine insensitive S-adenosylmethionine decarboxylase of E. coli is inhibited only at very high concentrations of methylglyoxal bis(guanylhydrazone). Some observations on the specificity of activation of the yeast and mammalian S-adenosylmethionine decarboxylases by short chain aliphatic diamines are also discussed.

New Aspects of Polyamine Biosynthesis in Eukaryotic Organisms

Abstract Some recent advances in the mechanism and control of enzymes that catalyze the synthesis of spermidine and spermine in eukaryotes are discussed. Aspects of the production of aliphatic polyamines by mammalian reproductive organs and malignant tumors are also considered.

Paradoxical enhancement of S-adenosylmethionine decarboxylase in rat tissues following administration of the specific inhibitor methyl glyoxal bis(guanylhydrazone)

Abstract Treatment of rats with large but sublethal doses of methyl glyoxal bis(guanylhydrazone), a potent in vitro inhibitor of animal S-adenosylmethionine decarboxylases, causes marked increases in the enzyme activity of extracts of kidney, ventral prostate, and testis which had been extensively dialyzed to remove any remaining drug. One day after administration of the inhibitor to female rats, the renal S-adenosylmethionine decarboxylase activity was 12 times the normal level and remained greatly enhanced for a further 24 hr. As indicated by decline in decarboxylase activity following depression of protein biosynthesis by injection of cycloheximide, the apparent half-life of the kidney enzyme in normal female rats is roughly 2 hr; in contrast, the apparent half-life of the enzyme is elevated to a value of more than 20 hr in animals that were previously treated with methyl glyoxal bis(guanylhydrazone). The increased renal S-adenosylmethionine decarboxylase activity following administration of the specific enzyme inhibitor in vivo may thus be due, at least in part, to stabilization of the enzyme against intracellular inactivation as a result either of direct combination of the enzyme protein with the inhibitor, or with substance(s) in the tissue whose levels are influenced by treatment with methyl glyoxal bis(guanylhydrazone).

Separation of two proteins required for synthesis of spermidine from S-adenosyl-L-methionine and putrescine in rat prostate☆

Abstract An enzyme catalyzing transfer of a propylamino group from exogenous decarboxylated S-adenosyl methionine to putrescine to form spermidine (spermidine synthase) has been separated from the putrescine-activated S-adenosyl methionine decarboxylase in soluble extracts of rat ventral prostate. Neither enzyme alone catalyzes the formation of significant quantities of spermidine from S-adenosyl methionine and putrescine, a reaction which proceeds readily on addition of suitable proportions of the two separable enzymes. Aspects of the interaction of these two proteins in the biosynthesis of spermidine by rat prostate are discussed.

Transglutaminases in mammalian reproductive tissues and fluids: relation to polyamine metabolism and semen coagulation

Unique forms of transglutaminases were found in rat coagulating (anterior prostate) gland and its secretion, and also in dorsolateral prostate but not in the ventral lobe of the gland. These forms of transglutaminases were especially reactive with saline-soluble seminal vesicle secretion proteins and their N,N-dimethylated derivatives as compared with N,N-dimethylcasein as amine acceptor protein substrates, and are electrophoretically separable from both the transglutaminase of rat liver and thrombin-activated Factor XIII of the blood clotting system. Transglutaminases of the type found in coagulating gland and dorsolateral prostate appear to be absent from a large number of other organs in the male rat, and also from the uterus, ovary, vagina, of virgin females and from ovary and the maternal and fetal parts of the placenta of late pregnancy. Studies on the role of coagulating gland transglutaminase in the clotting of seminal vesicle secretion protein that is the basis of semen coagulation are discussed. The aliphatic amines putrescine, spermidine and spermine are among the most active of low molecular weight primary amine compounds in rat tissues in serving as amine acceptor substrates for coagulating gland transglutaminases. Putrescine and related polyamines are incorporated into vesicular secretion proteins in the form of peptide bound γ-glutamyl derivatives, the free primary amine groups of which can then further react with other polypeptide-bound glutamine residues to form bis-(γ-glutamyl)polyamine cross-bridges in transglutaminase-catalyzed reactions.

Transglutaminase reactions associated with the rat semen clotting system: Modulation by macromolecular polyanions

Abstract The coagulation of rodent semen after ejaculation involves the establishment of ϵ-(γ-glutamyl)lysyl cross linkages between seminal vesicle secretion proteins as catalyzed by Ca ++ -dependent transglutaminases secreted by the coagulating (anterior prostate) gland. During enzymic clotting of rat vesicular secretion proteins, low molecular weight amines such as putrescine are incorporated into covalent linkage with proteins of both the coagulum and the clot liquor. Bulbourethral gland secretions and certain macromolecular polyanions (notably poly-L-glutamate) enhance the enzymic coagulation of rat vesicular secretion proteins and putrescine incorporation therein. The stimulatory macromolecular polyanions appear to exert their effects by facilitating the ability of vesicular secretion proteins to serve as transglutaminase amine acceptor substrates.

Spermidine synthesizing enzymes in baker's yeast

Summary Bakers yeast (Saccharomyces cerevisiae) is a rich source of two enzymes responsible for the synthesis of spermidine: (i) S-adenosyl methionine decarboxylase, and (ii) spermidine synthase, which catalyzes the synthesis of spermidine from decarboxylated S-adenosyl methionine and putrescine. The yeast S-adenosyl methionine decarboxylase has been purified about 400-fold, and largely separated from the bulk of spermidine synthase activity present in the crude yeast extracts. In marked contrast to the enzyme from E.coli , the yeast S-adenosyl methionine decarboxylase resembles a similar enzyme previously described in rat ventral prostate insofar as it is specifically enhanced by putrescine, and does not require Mg++ or any other dissociable metal cofactor. Some differences in the enzymic decarboxylation of S-adenosyl methionine by prostate, yeast, and E.coli are briefly discussed.

A flavoprotein responsible for the intense sulfhydryl oxidase activity of rat seminal vesicle secretion

Abstract A flavoprotein isolated in substantial yields from rat seminal vesicle secretion accounts for most if not all of the capacity of this fluid to catalyze the aerobic oxidation of a number of low molecular weight thiol compounds. The nature and possible physiological significance of this enzyme are discussed.

Enzymatic oxidation of some non-phosphorylated derivatives of dihydronicotinamide.

This paper concerns the partial purification and properties of an enzyme that catalyzes the oxidation of reduced ribosyl nicotinamide (NRH) by vitamin K3 (menadione) and certain other quinones. The enzyme is widely distributed in mammalian tissues. It is localized in the soluble portion of the cytoplasm. In the rat, the greatest activity of the enzyme was found in kidney, liver, heart and seminal vesicle. The purified enzyme also catalyzes the oxidation of certain N1-alkyl-dihydronicotinamides, but it is completely inert toward phosphorylated derivatives of dihydronicotinamide such as the reduced forms of nicotinamide mononucleotide (NMNH), and of di- and triphosphopyridine nucleotides (DPNH and TPNH).

Dissociation of putrescine-activated decarboxylation of S-adenosyl-L-methionine from the enzymic synthesis of spermidine and spermine by purified prostatic enzyme preparations.

Abstract The S-adenosyl-L-methionine decarboxylase that is specifically activated by putrescine or spermidine has been purified more than 500-fold from rat ventral prostate by a new procedure. At later stages of the purification, stoichiometric coupling of S-adenosyl-methionine decarboxylation and the synthesis of spermidine (in the presence of putrescine) and of spermine (in the presence of spermidine) is lost. Certain properties of the purified decarboxylase are described.