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Query: UMLS:C0042961 (volvulus)
 4,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A novel type of N-acetyltransferase, clearly different from the nuclear and cytosolic polyamine N-acetyltransferases of mammals, was recently found in the intestinal nematode Ascaris suum. The occurrence of this putrescine N-acetylating enzyme has also been noted in the filarial parasite Onchocerca volvulus. The enzyme was partially purified from adults of O. volvulus and A. suum by chromatography on DEAE-cellulose and cadaverine-Sepharose. Substrate specificities of the filarial enzyme resemble those of the N-acetyltransferase from A. suum, with respect to its preference for putrescine and other diamines above polyamines and histones. Additionally, both nematode enzymes acetylated histamine, whereas dopamine and serotonin were not accepted as substrates. The activities of the N-acetyltransferase from O. volvulus and A. suum were potently inhibited by the drug berenil; the type of inhibition was competitive with respect to putrescine. The inhibition constants for berenil were determined as 4.2 and 1.2 microM for the enzymes of O. volvulus and A. suum, the Km values for putrescine were found to be 330 microM and 250 microM, respectively. Putrescine N-acetyltransferase is discussed as a regulatory step in the degradation of excessive polyamines via polyamine oxidase to putrescine. At this branching point, putrescine is retained in the cell for de novo synthesis of spermidine and spermine, catabolized via diamine oxidase or acetylated to a suitable transport product for excretion.
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PMID:Putrescine N-acetyltransferase in Onchocerca volvulus and Ascaris suum, an enzyme which is involved in polyamine degradation and release of N-acetylputrescine. 232 51

Parasite-specific putrescine-N-acetyltransferase and polyamine oxidase, both involved in the reversed pathway of polyamine metabolism, were demonstrated for Ascaris suum and Onchocerca volvulus. Berenil-treatment was found to be correlated with accumulation of polyamines, especially spermine, obviously due to blockaded polyamine interconversion. Furthermore it was shown that added spermine to the culture medium led to the death of worms. These specificities might be exploited for chemotherapy of filarial infections. Polyamines are widely distributed in the nature. They are found in higher and lower eucaryotes and in procaryotes as well as in viruses (Tabor and Tabor, 1984). During the last years there have been many approaches to examine the role of polyamines in cell growth and differentiation in vertebrates (Tabor and Tabor, 1984; Pegg, 1986). The polyamine metabolism of parasites also has attracted increasing interest, e.g. in African trypanosomes the initial enzyme of polyamine synthesis - ornithine decarboxylase - has been exploited as a target for chemotherapy by using DFMO (DL alpha-difluoromethylornithine) (Bacchi et al., 1980; Bacchi et al., 1983; Fairlamb et al., 1985; Giffin et al., 1986). The polyamine metabolism of filaria and other helminths is still a neglected area of research, although there are reports about distribution pattern of polyamines and some peculiarities of polyamine metabolism in filarial worms (Srivastava et al., 1980; Wittich et al., 1987; Walter, 1988). DFMO and MGBG (methylglyoxal bis-(guanylhydrazone], both of which are potent inhibitors of polyamine synthesis in mammals, do not significantly effect the viability of filarial worms (Wittich et al., 1987).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The polyamine metabolism of filarial worms as chemotherapeutic target. 307 47

The characteristics and kinetic properties of an arylalkylamine N-acetyltransferase were studied in partially purified preparations of the human filarial parasite Onchocerca volvulus. The enzyme, which had a relative molecular mass (M(r)) of 37-38 kDa, catalyzed the acetylation of arylalkylamines but did not accept arylamines or polyamines as substrates. The optimal pH for enzyme activity was found to be 8.5 in TRIS-HCI. The apparent Michaelis constant (K(m)) and maximum velocity (Vmax) determined from Lineweaver-Burk plots for tryptamine were 1.8 microM and 29 nmol min-1 mg protein-1, respectively. Except for the catecholamines, the other arylalkylamines such as 5-hydroxytryptamine (5-HT), tyramine, and octopamine similarly exhibited high affinities and reaction rates. Whereas the enzyme is inhibited by metals and p-chloro-mercuribenzoate, it is inactivated neither by amethopterin nor by cystamine and is thereby distinguished from the mammalian arylamine N-acetyltransferase. Like other N-acetyltransferases whose function is the regulation of intracellular amine levels, the enzyme may have a role in the inactivation of excess biogenic amine in this parasite.
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PMID:Characterization of the arylalkylamine N-acetyltransferase in Onchocerca volvulus. 874 May 55