Isotopically sensitive branching in the formation of cyclic monoterpenes: proof that (-)-alpha-pinene and (-)-beta-pinene are synthesized by the same monoterpene cyclase via deprotonation of a common intermediate

Journal Article · Tue Aug 25 00:00:00 EDT 1987 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00391a025· OSTI ID:5607595

Croteau, R B; Wheeler, C J; Cane, D E; Ebert, R; Ha, H J

To determine whether the bicyclic monoterpene olefins (-)-alpha-pinene and (-)-beta-pinene arise biosynthetically from the same monoterpene cyclase by alternate deprotonations of a common carbocationic intermediate, the product distributions arising from the acyclic precursor (10-/sup 2/H/sub 3/,1-/sup 3/H)geranyl pyrophosphate were compared with those resulting from incubation of (1-3H)geranyl pyrophosphate with (-)-pinene cyclase from Salvia officinalis. Alteration in proportions of the olefinic products generated by the partially purified pinene cyclase resulted from the suppression of the formation of (-)-beta-pinene (C10 deprotonation) by a primary deuterium isotope effect with a compensating stimulation of the formation of (-)-alpha-pinene (C4 deprotonation). (-)-Pinene cyclase as well as (+)-pinene cyclase also exhibited a decrease in the proportion of the acyclic olefin myrcene generated from the deuteriated substrate, accompanied by a corresponding increase in the commitment to cyclized products. The observation of isotopically sensitive branching, in conjunction with quantitation of the magnitude of the secondary deuterium isotope effect on the overall rate of product formation by the (+)- and (-)-pinene cyclases as well as two other monoterpene cyclases from the same tissue, supports the biosynthetic origin of (-)-alpha-pinene and (-)-beta-pinene by alternative deprotonations of a common enzymatic intermediate. A biogenetic scheme consistent with these results is presented, and alternate proposals for the origin of the pinenes are addressed.

• Research Organization: Washington State Univ., Pullman
• OSTI ID: 5607595
• Journal Information: Biochemistry; (United States), Vol. 26:17
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CYCLASES
ENZYME ACTIVITY
DEUTERIUM
ISOTOPE EFFECTS
TERPENES
BIOSYNTHESIS
ISOTOPE DILUTION
PLANTS
TRITIUM COMPOUNDS
ENZYMES
HYDROGEN ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
LYASES
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
STABLE ISOTOPES
SYNTHESIS
TRACER TECHNIQUES
550201* - Biochemistry- Tracer Techniques