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Titolo:
Purification and kinetic properties of betaine-homocysteine methyltransferase from Aphanothece halophytica
Autore:
Waditee, R; Incharoensakdi, A;
Indirizzi:
Chulalongkorn Univ, Fac Sci, Dept Biochem, Lab Biochem Prod, Bangkok 10330, Thailand Chulalongkorn Univ Bangkok Thailand 10330 Prod, Bangkok 10330, Thailand
Titolo Testata:
CURRENT MICROBIOLOGY
fascicolo: 2, volume: 43, anno: 2001,
pagine: 107 - 111
SICI:
0343-8651(200108)43:2<107:PAKPOB>2.0.ZU;2-W
Fonte:
ISI
Lingua:
ENG
Soggetto:
HALOTOLERANT CYANOBACTERIUM; RAT-LIVER; SALT-STRESS; HUMAN GENE; GLYCINEBETAINE; METHIONINE; BIOSYNTHESIS; ACCUMULATION; CARBOXYLASE; EXPRESSION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
25
Recensione:
Indirizzi per estratti:
Indirizzo: Incharoensakdi, A Chulalongkorn Univ, Fac Sci, Dept Biochem, Lab Biochem Prod, Bangkok 10330, Thailand Chulalongkorn Univ Bangkok Thailand 10330 30, Thailand
Citazione:
R. Waditee e A. Incharoensakdi, "Purification and kinetic properties of betaine-homocysteine methyltransferase from Aphanothece halophytica", CURR MICROB, 43(2), 2001, pp. 107-111

Abstract

Betaine-homocysteine methyl transferase (BHMT) from Aphanothece halophytica was purified to homogeneity by hydroxyapatite, DEAE-Sepharose CL-GB and Sephadex G-200 column chromatography. A 24-fold purification and 11% overallyield were achieved with a specific activity of 595 nmol h(-1) mg(-1). Thesubunit molecular weight was determined to be 45 kDa by sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE), and the native enzyme was found to have a molecular weight of 350 kDa, suggesting an octameric structure of the enzyme. The enzyme shows optimum activity at 37 degreesC, pH 7.5. The apparent Km values for glycinebetaine and L-homocysteine were 4.3 mM and 1.3 mM, respectively. The enzyme was 70% inactivated by 5 mM dimethylglycine whereas the same concentration of sarcosine slightly inactivated the enzyme. Two analogs of glycinebetaine were also tested for enzyme inactivation and it was found that 5 mM choline inactivated 60% of the enzyme activity and 2.5 mM betaine aldehyde completely abolished the enzyme activity. NaCl at 200 mM or higher also completely inactivated the enzyme.

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Documento generato il 13/07/20 alle ore 07:38:07