Premium
Identification of sources of hydrogen atoms in fatty acids synthesized using deuterated water and stereospecifically deuterium labelled NADPH by gas chromatographic mass spectrometric analysis
Author(s) -
Seyama Yousuke,
Kawaguchi Akihiko,
Kasama Takeshi,
Sasaki Keizo,
Arai Kazumi,
Okuda Shigenobu,
Yamakawa Tamio
Publication year - 1978
Publication title -
biomedical mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0306-042X
DOI - 10.1002/bms.1200050507
Subject(s) - deuterium , chemistry , methylene , stereospecificity , hydrogen , stereochemistry , medicinal chemistry , organic chemistry , catalysis , physics , quantum mechanics
The mechanism of hydrogen incorporation into fatty acids with rat liver fatty acid synthetase was investigated. The distributions of deuterium atoms incorporated into the fatty acids from D 2 O and stereospecifically deuterium labelled NADPH were determined by mass chromatography. In palmitic acid, 14 deuterium atoms were incorporated from D 2 O and were found on the even‐numbered methylene carbon atoms (two deuterium atoms per carbon atom). Seven of these 14 deuterium atoms were incorporated as the result of deuterium–hydrogen exchange between the methylene group of malonyl‐CoA and C 2 O and D 2 O. Seven deuterium atoms came from the 4α‐position of NADPH and were found on the odd‐numbered methylene carbon atoms (one deuterium atom per carbon atom). Seven deuterium atoms from the 4β‐position of NADPH were also found on the odd‐numbered methylene carbon atoms (one deuterium atom per carbon atom). The stereospecificities of β‐ketoacyl reductase and enoyl reductase for NADPH were determined with S ‐acetoacetyl‐ N ‐acetyl‐cysteamine and S ‐crotonyl‐ N ‐acetylcysteamine as substrates. The products, S ‐hydroxybutryl‐ N ‐acetyl‐cysteamine and S ‐butyryl‐ N ‐acetylcysteamine, respectively, were analysed by gas chromatography mass spectrometry; the results indicated that the β‐ketoacyl reductase had B stereospecificity and enoyl reductase had A stereospecificity for NADPH.