title: Enzymatic synthesis and structure of precorrin-3, a trimethyldipyrrocorphin intermediate in vitamin B12 biosynthesis.
abstract: The trimethylated intermediate of vitamin B12 (corrin) biosynthesis, precorrin-3, was produced from various 13C-enriched isotopomers of 5-aminolevulinic acid (ALA), using a multiple-enzyme system containing ALA dehydratase, porphobilinogen deaminase, uro'gen III synthetase, and the S-adenosyl-L-methionine-(SAM)-dependent uro'gen III methyltransferase (M-1) and precorrin-2 methyltransferase (M-2) in the presence of [13C]SAM. Structural analysis of the resulting product, precorrin-3, reveals a close similarity to precorrin-2 but with several subtle differences in the conjugated array of C = C and C = N bonds which reflect the presence of the new C-methyl group at C20 and its influence on the electronic distribution in the dipyrrocorphin chromophore. The implications of this structure for corrin biosynthesis are discussed.
authors.affiliation: Department of Chemistry, Texas A&M University, College Station 77843-3255.
authors.forename: M J
authors.initials: MJ
authors.lastname: Warren
authors.forename: C A
authors.initials: CA
authors.lastname: Roessner
authors.forename: S
authors.initials: S
authors.lastname: Ozaki
authors.forename: N J
authors.initials: NJ
authors.lastname: Stolowich
authors.forename: P J
authors.initials: PJ
authors.lastname: Santander
authors.forename: A I
authors.initials: AI
authors.lastname: Scott
mesh_terms: D004926:Escherichia coli / Q000235:genetics; D005822:Genetic Vectors; D011163:Hydroxymethylbilane Synthase / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008780:Methyltransferases / Q000737:chemistry; D011162:Porphobilinogen / Q000737:chemistry; D000623:Porphobilinogen Synthase / Q000737:chemistry; D011549:Pseudomonas / Q000235:genetics; D014576:Uroporphyrinogen III Synthetase / Q000737:chemistry; D014578:Uroporphyrins / Q000096:biosynthesis* / Q000737:chemistry; D014805:Vitamin B 12 / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D014578:Uroporphyrins; D011162:Porphobilinogen; D008780:Methyltransferases; C060508:uroporphyrin-III C-methyltransferase; D011163:Hydroxymethylbilane Synthase; D000623:Porphobilinogen Synthase; D014576:Uroporphyrinogen III Synthetase; D014805:Vitamin B 12