Endogenously generated 5‐hydroperoxyeicosatetraenoic acid is the preferred substrate for human leukocyte leukotriene A4 synthase activity

FEBS Letters

Samuelsson, Bengt¹  Scheffer, Mark M.¹  Puustinen, Tapio¹ 

[1] Department of Physiological Chemistry, Karolinska Institutet, S-104 01 Stockholm, Sweden

关键词: 5-Lipoxygenase;    Leukotriene A4 synthase;    Leukocyte;    Arachidonic acid;    Reaction mechanism;    (Human);    5-HPETE;    5-hydroperoxyeicosatetraenoic acid;    LT;    leukotriene;    15-HPETE;    15-hydroperoxyeicosatetraenoic acid;    HPLC;    high-performance liquid chromatography;    GC-MS;    gas chromatography-mass spectrometry;   

DOI  :  10.1016/0014-5793(87)80675-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

A single protein from human leukocytes possesses both 5-lipoxygenase and leukotriene A₄ (LTA₄) synthase activities. It has been reported that LTA₄ production is more efficient when the enzyme utilizes arachidonic acid, than when 5-HPETE is exogenously supplied as substrate. In the present study, human leukocyte homogenate 100 000 × g supernatant was incubated with 100 μM octadeuterated arachidonic acid and exogenous 5-HPETE (0–80 μM), and the isotopic composition of LTA₄ hydrolysis products was determined by gas chromatography-mass spectrometry. Even though 100 μM deuterated arachidonic acid results in 20–30 μM deuterated 5-HPETE, 80 μM exogenous 5-HPETE in the incubation could reduce the amount of deuterated LTA₄ by only approx. 20%. The present study would thus indicate that the arachidonic acid moiety is preferentially converted to LTA₄ in a concerted reaction without dissociation of a 5-HPETE intermediate.

【 授权许可】

Unknown