Stereochemical course of enzyme-catalyzed aminopropyl transfer: spermidine synthase

Conference · Thu May 01 04:00:00 EDT 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:5151107

Kullberg, D W; Orr, G R; Coward, J K

The R and S enantionmers of S-adenosyl-3-(/sup 2/H)3-(methylthio)-1-propylamine (decarboxylated S-adenosylmethionine), previously synthesized in this laboratory, were incubated with (1,4-/sup 2/H/sub 4/)-putrescine in the presence of spermidine synthase from E. coli. The resulting chiral (/sup 2/H/sub 5/)spermidines were isolated and converted to their N/sub 1/,N/sub 7/-dibocspermidine-N/sub 4/-(1S,4R)-camphanamides. The derivatives were analyzed by 500 MHz /sup 1/H-NMR and the configuration of the chiral center assigned by correlation with the spectra of synthetic chiral (/sup 2/H/sub 3/)dibocspermidine camphanamide standards. The enzyme-catalyzed aminopropyl transfer was shown to occur with net retention of configuration, indicative of a double-displacement mechanism. This result concurs with that of a previous steady-state kinetics study of spermidine synthase isolated from E. coli, but contradicts the single-displacement mechanism suggested by a stereochemical analysis of chiral spermidines biosynthesized in E. coli treated with chirally deuterated methionines. It also indicates that this aminopropyltransferase is mechanistically distinct from the methyltransferases, which have been shown to act via a single-displacement mechanism (net inversion at -CH/sub 3/) in all cases studied to date.

• Research Organization: Rensselaer Polytechnic Institute, Troy, NY
• OSTI ID: 5151107
• Report Number(s): CONF-8606151-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:6
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
550600 -- Medicine
59 BASIC BIOLOGICAL SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
AMINES
AMINO ACIDS
AMINOTRANSFERASES
BACTERIA
BIOCHEMICAL REACTION KINETICS
CARBOXYLIC ACIDS
DEUTERIUM
DRUGS
ENZYMES
ESCHERICHIA COLI
HYDROGEN ISOTOPES
ISOTOPES
KINETICS
LIGHT NUCLEI
LIPOTROPIC FACTORS
METHIONINE
MICROORGANISMS
NITROGEN TRANSFERASES
NMR SPECTRA
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
REACTION KINETICS
SPECTRA
SPERMIDINE
STABLE ISOTOPES
STEREOCHEMISTRY
TRANSFERASES