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N-beta-methylamino-L-alanine : a non-protein amino acid incorporated into protein

University of British Columbia

N-β-methylamino-L-alanine (BMAA) is a naturally-occurring toxin produced in cyanobacteria that has been linked to neurological degeneration. Efforts to study and quantify BMAA in the environment are hampered by two biologically-occurring isomers, N-(2- aminoethyl)glycine (AEG) and 2,4-diaminobutyric acid (DAB), that exist in very low concentrations in many sample matrices, indicating a need for improved analytical methods. The first objective of this thesis is to develop an accurate, precise and sensitive method for the analysis of BMAA and the isomers AEG and DAB that is applicable to a wide variety of sample matrices. A method for complete chromatographic separation of the isomers was developed using chemical derivatization, reversed phase chromatography and tandem mass spectrometry, and was validated with cyanobacteria-containing natural health products. The mechanism of toxicity of BMAA is not fully understood, and previous studies have shown an association between BMAA and protein. The second objective of this thesis is to determine whether BMAA is incorporated into protein via a modified proteomics approach used to identify peptides containing BMAA in tissue from post-mortem human patients. This approach identified BMAA in proteins isolated from the frontal lobe of Amyotrophic Lateral Sclerosis (ALS), Alzheimer’s disease (AD), and control patients. To determine whether BMAA incorporation into protein occurs as an error in synthesis, a cell-free expression system was challenged with a deficiency of specific amino acids and supplemented with BMAA. BMAA was incorporated into protein via an error in synthesis. Together, these data demonstrate accurate methods for quantification of BMAA, a route of exposure through dietary products, and a potential mechanism for storage of BMAA in proteins.

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2014-10-14

Attribution-NonCommercial-NoDerivs 2.5 Canada

http://hdl.handle.net/2429/50730

Biochemistry and Molecular Biology

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/2.5/ca/