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Alpha-saturation and terminal events in dolichol biosynthesis

Journal Article · · J. Biol. Chem.; (United States)
OSTI ID:6528980
; ;

Incubations of 10,000 X g supernatant from rat liver with (/sup 3/H)mevalonate were performed and the labeling of polyprenols was studied. It was demonstrated that factors like pH, substrate concentration, and presence of detergent not only greatly influence the total incorporation but also the relative distribution of radioactivity among the isoprenologues. The synthesis was shown to be extremely sensitive to Triton X-100. Substrate concentrations of 1 and 100 microM mostly gave polyprenols with 18 and 20 isoprenes, respectively. At a given substrate concentration, pH 6.5 resulted in shorter polyprenols than did pH 7.5. Ozonolytic fragmentation demonstrated that in the initial phase of incubation, polyprenols are elongated by 1 isoprene residue and saturated to give dolichols. No substantial dephosphorylation of polyprenyl phosphates to the free alcohol occurred. The production of dolichol in vitro was shown to utilize NADH for the saturation event. This seemed to occur concomitantly with the synthesis. alpha-Saturation of polyprenyl-P could not be achieved with the procedures employed. It is proposed that the synthesis of dolichol and dolichyl-P do not share the same terminal steps; saturation and terminal isoprene condensation occur in cooperation; and substrate concentration and pH influence the terminal enzyme(s) and the nature of the final product in the polyprenol biosynthesis.

Research Organization:
Univ. of Stockholm, Sweden
OSTI ID:
6528980
Journal Information:
J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 9; ISSN JBCHA
Country of Publication:
United States
Language:
English

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Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BIOCHEMICAL REACTION KINETICS
BIOSYNTHESIS
BODY
CARBOXYLIC ACIDS
COENZYMES
DIGESTIVE SYSTEM
ENZYMES
ESTERASES
GLANDS
HYDROLASES
HYDROXY ACIDS
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LIPIDS
LIVER
MAMMALS
MEVALONIC ACID
NAD
NUCLEOTIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
OZONE
PHOSPHATASES
RATS
REACTION KINETICS
RODENTS
SYNTHESIS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES