Kinetics of long-chain (Sphingoid) base biosynthesis in intact LM cells: effects of varying the extracellular concentrations of serine and fatty acid precursors of this pathway

Journal Article · Tue Jan 12 04:00:00 EST 1988 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00401a051· OSTI ID:5357765

Merrill, Jr, A H; Wang, E; Mullins, R E

Serine palmitoyltransferase (EC 2.3.1.50) catalyzes the condensation of L-serine and palmitoyl-CoA to yield 3-ketosphinganine in the first unique reaction of long-chain (sphingoid) base biosynthesis. The kinetic effects of changing the extracellular concentrations of the precursors for this pathway were studied with LM cells by following the incorporation of L-(3-/sup 14/C) serine into the long-chain base (i.e., sphinganine and sphingenine) backbones of complex sphingolipids. (/sup 14/C)Serine was taken up by the cells and rapidly reached steady-state concentration similar to those of the medium. From the cellular (/sup 14/C) serine concentrations and specific activities, the apparent V/sub max/ and K/sub m/ values for long-chain base synthesis were determined and found to be essentially identical with those for serine palmitoyltransferase assayed in vitro. The other precursor, palmitic acid, was also taken up rapidly and increased long-chain base biosynthesis in a concentration-dependent manner. This effect was limited to palmitic acid and matched the know specificity of serine palmitoyltransferase for saturated fatty acyl-CoA's of 16 +/- 1 carbon atoms. These studies delineate the influence of extracellular precursors on the formation of the sphingolipid backbone and suggest that the kinetic properties of serine palmitoyltransferase govern this behavior of long-chain base synthesis in intact cells.

• Research Organization: Emory Univ. School of Medicine, Atlanta, GA
• OSTI ID: 5357765
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 27:1; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACID SEQUENCE
AMINO ACIDS
ANIMAL CELLS
ANIMALS
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL PATHWAYS
BIOSYNTHESIS
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
ENZYMES
ESTERS
HEXADECANOIC ACID
HYDROXY ACIDS
KINETICS
LABELLED COMPOUNDS
LIPIDS
MAMMALS
MICE
MOLECULAR STRUCTURE
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PHOSPHOLIPIDS
REACTION KINETICS
RODENTS
SERINE
SYNTHESIS
TRANSFERASES
TRITIUM COMPOUNDS
VERTEBRATES