Determination of S-adenosyl-l-methionine in fruits by capillary electrophoresis.
BACKGROUND
S-adenosyl-l-methionine (SAM) plays an important role in many biochemical reactions in plants. It is mainly used as a methyl donor for methylation reactions, but it also participates in, for example, the biosynthesis of polyamines and the plant hormone ethylene.


OBJECTIVE
To develop a fast capillary electrophoresis technique to separate SAM in fruits and fruit juices without any pre-purification steps.


METHODS
Four different extraction solutions and two extraction times were tested, of which 5% trichloroacetic acid (TCA) for 10 min was found most suited. A glycine : phosphate buffer (200 : 50 mm, pH 2.5) was found optimal to analyse SAM in TCA extracts. Analyses were preformed on different climacteric and non-climacteric fruits and fruit juices. The calibration curve was created in degraded tomato extract. The CE-method was compared with a more conventional HPLC method described in literature.


RESULTS
The CE technique made it possible to completely separate the S,S- and R,S-diastereoisomeric forms of SAM. The CE method proved to be very fast (20 min total running time instead of 42 min) and more sensitive (limit of detection of 0.5 µm instead of 1 µm) compared with the conventional HPLC method.


CONCLUSIONS
Fast measurements of SAM in fruits and juices are favoured by capillary electrophoresis in a 200 : 50 mm glycine : phosphate (pH 2.5) buffer system.
Van de Poel
Bram
B
Department of Biosystems, Katholieke Universiteit Leuven, Willem de Croylaan 42, Leuven, Belgium. bram.vandepoel@biw.kuleuven.be
Bulens
Inge
I
Lagrain
Pieter
P
Pollet
Jeroen
J
Hertog
Maarten L A T M
ML
Lammertyn
Jeroen
J
De Proft
Maurice P
MP
Nicolaï
Bart M
BM
Geeraerd
Annemie H
AH
D002021:Buffers; D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D019075:Electrophoresis, Capillary; D005638:Fruit / Q000737:chemistry*; D007202:Indicators and Reagents; D018551:Solanum lycopersicum / Q000737:chemistry; D010936:Plant Extracts / Q000032:analysis; D012436:S-Adenosylmethionine / Q000032:analysis* / Q000302:isolation & purification; D012996:Solutions; D013237:Stereoisomerism
D002021:Buffers; D007202:Indicators and Reagents; D010936:Plant Extracts; D012996:Solutions; D012436:S-Adenosylmethionine