title: Kinetic and molecular orbital analyses of dicarboxylic acylcarnitine methylesterification show that derivatization may affect the screening of newborns by tandem mass spectrometry.
abstract: Newborns are routinely screened for organic acidemias by acylcarnitine analysis. We previously reported the partial catalytic methylesterification of dicarboxylic acylcarnitines by benzenesulfonic acid moiety in the solid extraction cartridge during extraction from serum. Since the diagnosis of organic acidemias by tandem mass spectrometry is affected by the higher molecular weight of these derivatized acylcarnitines, we investigated the methylesterification conditions. The kinetic constants for the methylesterification of carboxyl groups on the acyl and carnitine sides of carnitine were 2.5 and 0.24h(-1), respectively. The physical basis underlying this difference in methylesterification rates was clarified theoretically, illustrating that methylesterification during extraction proceeds easily and must be prevented.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan. Electronic address: maeda@phar.nagoya-cu.ac.jp.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Maeda
authors.affiliation: School of Medicine, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake 470-1192, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Nakajima
authors.affiliation: Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan.
authors.forename: Kana
authors.initials: K
authors.lastname: Gotoh
authors.affiliation: Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Hotta
authors.affiliation: Graduate School of Medical Sciences, Nagoya City University, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Kataoka
authors.affiliation: Aichi-Gakuin University, School of Pharmacy, 2-11 Suemori-dori, Chikusa-ku, Nagoya 464-8651, Japan.
authors.forename: Naruji
authors.initials: N
authors.lastname: Sugiyama
authors.affiliation: Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Shirai
authors.affiliation: School of Medicine, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake 470-1192, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ito
authors.affiliation: Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan; Graduate School of Medical Sciences, Nagoya City University, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kimura
mesh_terms: D002331:Carnitine / Q000031:analogs & derivatives* / Q000097:blood / Q000737:chemistry; D003998:Dicarboxylic Acids / Q000097:blood* / Q000737:chemistry*; D004951:Esterification; D006801:Humans; D007231:Infant, Newborn; D007700:Kinetics; D008745:Methylation; D015394:Molecular Structure; D015997:Neonatal Screening / Q000379:methods*; D011789:Quantum Theory; D053719:Tandem Mass Spectrometry
chemical_list: D003998:Dicarboxylic Acids; C116917:acylcarnitine; D002331:Carnitine
keywords: Acylcarnitine; Carnitine; Methylesterification; Newborn screening; Tandem mass spectrometry