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Titolo:
DELTA-6-DESATURASE AND DELTA-5-DESATURASE ACTIVITIES IN THE HUMAN FETAL LIVER - KINETIC ASPECTS
Autore:
RODRIGUEZ A; SARDA P; NESSMANN C; BOULOT P; LEGER CL; DESCOMPS B;
Indirizzi:
FAC MED MONTPELLIER,INST BIOL,LAB BIOL & BIOCHIM LIPIDES,EA DRED 2033,BLVD HENRI IV F-34060 MONTPELLIER FRANCE FAC MED MONTPELLIER,INST BIOL,LAB BIOL & BIOCHIM LIPIDES,EA DRED 2033F-34060 MONTPELLIER FRANCE CHU MONTPELLIER,HOP ARNAUD DE VILLENEUVE,SERV PEDIAT 2 MONTPELLIER FRANCE CHU MONTPELLIER,HOP ARNAUD DE VILLENEUVE,SERV GYNECOL OBSTET MONTPELLIER FRANCE HOP ROBERT DEBRE,SERV BIOL DEV & REPROD F-75019 PARIS FRANCE
Titolo Testata:
Journal of lipid research
fascicolo: 9, volume: 39, anno: 1998,
pagine: 1825 - 1832
SICI:
0022-2275(1998)39:9<1825:DADAIT>2.0.ZU;2-4
Fonte:
ISI
Lingua:
ENG
Soggetto:
ESSENTIAL FATTY-ACIDS; GAMMA-LINOLENIC ACID; GUINEA-PIGS; MICROSOMES; CHROMATOGRAPHY; BIOSYNTHESIS; INFANT;
Keywords:
KINETIC; DESATURASE ACTIVITY; HUMAN FETUS; LIVER; MICROSOMES; ENDOGENOUS SUBSTRATE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
27
Recensione:
Indirizzi per estratti:
Citazione:
A. Rodriguez et al., "DELTA-6-DESATURASE AND DELTA-5-DESATURASE ACTIVITIES IN THE HUMAN FETAL LIVER - KINETIC ASPECTS", Journal of lipid research, 39(9), 1998, pp. 1825-1832

Abstract

Delta 6- and Delta 5-desaturase activities were studied in human fetal liver microsomes obtained after legally approved therapeutic abortion. Enzyme activities were measured by a radiochemical method using reverse-phase high performance liquid chromatography (HPLC), Free and phospholipid fatty acids were assessed in each liver sample by a combination of thin-layer chromatography (TLC) and gas-liquid chromatography (GLC) procedures. The kinetic measurements showed higher Delta 6-desaturase activity for the n-3 series than for the n-6 series. Apparent K-mof 6.5, 3.9, and 24.5 mu M and V-m of 7.5, 9.1, and 24.4 pmol.min(-1).mg(-1) were obtained, respectively, for 18:2n-6 Delta 6-, 20:3n-6 Delta 5-, and 18:3n-3 Delta 6-desaturases. Beyond 30, 20, and 60 mu M of 18:2n-6, 20:3n-6, and 18:3n-3 concentration, respectively, the enzyme activity deviated from Michaelis-Menten kinetics, suggesting an inhibition by excess substrate which is unlikely to occur in vivo as endogenous substrate concentration is much lower. We observed a breakdown in linearity between desaturase activity and microsomal protein concentration beyond 4-5 mg microsomal protein, whatever the enzyme or substrate. Both this phenomenon and the inhibition due to excess substrate should be taken into account in the determination of Delta 6- and Delta 5-desaturase activities, Comparison of concentrations of the respectiveendogenous substrates and the kinetic constants of each enzyme suggested that the higher Delta 6-desaturase activity observed for the n-3 series than for the n-6 series is not physiologically relevant in humanfetal liver.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 28/11/20 alle ore 12:47:48