Abstract
Betaine-homocysteine methyl transferase (BHMT) from Aphanothece halophytica was purified to homogeneity by hydroxyapatite, DEAE-Sepharose CL-6B and Sephadex G-200 column chromatography. A 24-fold purification and 11% overall yield were achieved with a specific activity of 595 nmol h−1 mg−1. The subunit molecular weight was determined to be 45 kDa by sodium dodecyl sulfate-polyacrylamide 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°C, 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.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
Author information
Authors and Affiliations
Additional information
Received: 6 December 2000 / Accepted: 10 January 2001
Rights and permissions
About this article
Cite this article
Waditee, R., Incharoensakdi, A. Purification and Kinetic Properties of Betaine-Homocysteine Methyltransferase from Aphanothece halophytica . Curr Microbiol 43, 107–111 (2001). https://doi.org/10.1007/s002840010270
Issue Date:
DOI: https://doi.org/10.1007/s002840010270