Natural rubber biosynthesis—A living carbocationic polymerization?

Puskás, Judit E.; Gautriaud, Emilie; Deffieux, Alain; Kennedy, Joseph P.

doi:10.1016/j.progpolymsci.2006.05.002

Cited by 98 publications

(81 citation statements)

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“…In cholesterol biosynthesis, PP i is released in several of the early and foundational steps leading to the production of steroid hormones and vitamin D (25). Likewise, natural rubber is synthesized from allylic diphosphate and polymers of isopentenyl diphosphate (IPP), releasing one PP i per IPP incorporated by this rate-limiting reaction (26,27). Solvent-tolerant PPAs could be used to drive forward the initiation and elongation reactions of rubber and cholesterol-derived compounds by performing the reactions in extracting reagents that enhance reactant and product solubility.…”

mentioning

confidence: 99%

Archaeal Inorganic Pyrophosphatase Displays Robust Activity under High-Salt Conditions and in Organic Solvents

McMillan

Hepowit

Maupin-Furlow

2016

Appl Environ Microbiol

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Soluble inorganic pyrophosphatases (PPAs) that hydrolyze inorganic pyrophosphate (PP i ) to orthophosphate (P i ) are commonly used to accelerate and detect biosynthetic reactions that generate PP i as a by-product. Current PPAs are inactivated by high salt concentrations and organic solvents, which limits the extent of their use. Here we report a class A type PPA of the haloarchaeon Haloferax volcanii (HvPPA) that is thermostable and displays robust PP i -hydrolyzing activity under conditions of 25% (vol/vol) organic solvent and salt concentrations from 25 mM to 3 M. HvPPA was purified to homogeneity as a homohexamer by a rapid two-step method and was found to display non-Michaelis-Menten kinetics with a V max of 465 U · mg ؊1 for PP i hydrolysis (optimal at 42°C and pH 8.5) and Hill coefficients that indicated cooperative binding to PP i and Mg 2؉ . Similarly to other class A type PPAs, HvPPA was inhibited by sodium fluoride; however, hierarchical clustering and three-dimensional (3D) homology modeling revealed HvPPA to be distinct in structure from characterized PPAs. In particular, HvPPA was highly negative in surface charge, which explained its extreme resistance to organic solvents. To demonstrate that HvPPA could drive thermodynamically unfavorable reactions to completion under conditions of reduced water activity, a novel coupled assay was developed; HvPPA hydrolyzed the PP i by-product generated in 2 M NaCl by UbaA (a "salt-loving" noncanonical E1 enzyme that adenylates ubiquitin-like proteins in the presence of ATP). Overall, we demonstrate HvPPA to be useful for hydrolyzing PP i under conditions of reduced water activity that are a hurdle to current PPA-based technologies. Inorganic pyrophosphatases (PPAs) (EC 3.6.1.1) catalyze the hydrolysis of the phosphoanhydride bond of inorganic pyrophosphate (PP i ) (P 2 O 7 4Ϫ ) to form 2 mol of orthophosphate (P i ) (PO 4 3Ϫ ) (1). PP i is a common by-product of metabolism, including the biosynthesis of DNA, RNA, protein, peptidoglycan, lipids (e.g., cholesterol), cellulose, starch, and other biopolymers (2). PP i is also formed during the posttranslational modification of proteins, including adenylation, uridylation, and ubiquitylation (2).The hydrolysis of PP i by PPA releases a considerable amount of energy (⌬G=°ϭ Ϫ19.2 kJ/mol) that can drive unfavorable biochemical transformations to completion. One example is in the synthesis of DNA by DNA polymerase. In this endergonic (⌬G=°ϭ ϩ2.1 kJ/mol) reaction, the 3=-hydroxyl group of the nucleotide that resides at the 3= end of the growing DNA strand serves as a nucleophile in the attack of the ␣ phosphorus of the incoming deoxynucleoside 5=-triphosphate (dNTP), thus releasing PP i (2). The polymerization of DNA is highly dependent on PPA to hydrolyze the energy-rich PP i to 2P i and to drive the synthesis reaction forward (2). Under standard conditions, DNA polymerase alone converts DNA to dNTPs.PPAs are used in a wide variety of biotechnology applications based on the ability of these enzymes to drive reactions f...

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mentioning

confidence: 99%

Archaeal Inorganic Pyrophosphatase Displays Robust Activity under High-Salt Conditions and in Organic Solvents

McMillan

Hepowit

Maupin-Furlow

2016

Appl Environ Microbiol

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“…In addition, mutation of enzyme is a new technique to modify the catalyst function and the mutant was very useful for mechanistic studies, which is an important future direction. Furthermore, a recent paper showed that enzymatic catalysis bridges the study on the in vivo biosynthesis of natural biomacromolecules and that on the in vitro polymerization for synthesis of such polymers, 83) suggesting also a future direction of research.…”

Section: Resultsmentioning

confidence: 99%

New developments of polysaccharide synthesis via enzymatic polymerization

Kobayashi

2007

Proceedings of the Japan Academy. Ser. B: Physical and Biologic

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This review focuses on the in vitro synthesis of polysaccharides, the method of which is ''enzymatic polymerization'' mainly developed by our group. Polysaccharides are formed by repeated glycosylation reactions between a glycosyl donor and a glycosyl acceptor. A hydrolysis enzyme was found very efficient as catalyst, where the monomer is designed based on the new concept of a ''transition-state analogue substrate'' (TSAS); sugar fluoride monomers for polycondensation and sugar oxazoline monomers for ring-opening polyaddition. Enzymatic polymerization enabled the first in vitro synthesis of natural polysaccharides such as cellulose, xylan, chitin, hyaluronan and chondroitin, and also of unnatural polysaccharides such as a cellulose-chitin hybrid, a hyaluronan-chondroitin hybrid, and others. Supercatalysis of hyaluronidase was disclosed as unusual enzymatic multi-catalyst functions. Mutant enzymes were very useful for synthetic and mechanistic studies. In situ observations of enzymatic polymerization by SEM, TEM, and combined SAS methods revealed mechanisms of the polymerization and of the self-assembling of high-order molecular structure formed by elongating polysaccharide molecules.

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“…There are a large number of low molar mass analogs and derivatives of glycerol phosphate, playing an important role in biology in the so-called "Glycerol Metabolic Pathway". In addition, monoesters of phosphoric acid are considered to be components of polyisobutylene synthesis in plants, an active field of synthetic polymer chemistry [79]: the more than 1000 papers related to "Organophosphates" is indicative of the biological importance of phosphates (such as glycerol phosphate) in biology.…”

Section: Reactions Of Phosphoric Acid With Glycerolmentioning

confidence: 99%