Cryo-bioorganic chemistry: molecular interactions at low temperature

Vajda, Tamás

doi:10.1007/s000180050441

Cited by 28 publications

(15 citation statements)

References 89 publications

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“…Owing to the equilibrium between the ice phase and the eutectic phase, ice crystal growth only ceases when a certain solute concentration has been reached in the eutectic phase 15 . Thus, more dilute starting conditions do not lead to a more dilute eutectic phase but rather reduce its volume until the same equilibrium concentration is reached.…”

Section: Resultsmentioning

confidence: 99%

“…When an aqueous solution of ions or other solutes is cooled to below its freezing point, a biphasic system is formed, whereby solutes are excluded from the growing ice crystals and are concentrated in an interstitial liquid brine, the eutectic phase. Ice crystal growth causes the progressive dehydration and concentration of solutes 15 , accelerating many chemical reactions, notably the formation of RNA oligomers by non-enzymatic polymerization of activated nucleotides [16][17][18][19] . Thus, ice has the potential to provide, in situ, starting materials for prebiotic RNA evolution.…”

Section: Resultsmentioning

confidence: 99%

“…Owing to the concentrating effect of eutectic phase formation, ribozyme-catalysed RNA replication can proceed from starting mixtures containing as little as 1 mM Mg 2 + and 10 µM ribonucleotide triphosphates. The strength of this concentration effect is inversely proportional to the total solute level 15,19 and consequently dependent on the salinity of the environment; it would therefore have been best realized in a freshwater environment. It is notable that other prebiotically relevant processes such as vesicle formation, concentration of solutes by thermophoresis and the non-enzymatic condensation of activated mononucleotides are also inhibited by saline environments 37,38 .…”

Section: Discussionmentioning

confidence: 99%

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Ice as a protocellular medium for RNA replication

et al. 2010

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A crucial transition in the origin of life was the emergence of an informational polymer capable of self-replication and its compartmentalization within protocellular structures. We show that the physicochemical properties of ice, a simple medium widespread on a temperate early Earth, could have mediated this transition prior to the advent of membraneous protocells. Ice not only promotes the activity of an RNA polymerase ribozyme but also protects it from hydrolytic degradation, enabling the synthesis of exceptionally long replication products. Ice furthermore relieves the dependence of RNA replication on prebiotically implausible substrate concentrations, while providing quasicellular compartmentalization within the intricate microstructure of the eutectic phase. Eutectic ice phases had previously been shown to promote the de novo synthesis of nucleotide precursors, as well as the condensation of activated nucleotides into random RNA oligomers. Our results support a wider role for ice as a predisposed environment, promoting all the steps from prebiotic synthesis to the emergence of RNA self-replication and precellular Darwinian evolution.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Ice as a protocellular medium for RNA replication

et al. 2010

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“…The final concentration of RNA and salts in the unfrozen liquid inclusions depends on the freezing temperature, the specific nature of those solutes, and their initial (prefreezing) concentration. The concentration effect can account for the increase in rate of intermolecular reactions as well as the decrease in rate caused by the addition of salts, buffers, and other solutes that lower the freezing point and thereby limit the extent to which RNA is concentrated (Pincock 1969;Vajda 1999). The circularization of the HPR (ligation in cis) is a unimolecular reaction, and its rate is therefore not expected to be concentration-dependent.…”

Section: What Role Does Concentration Of Rna or Salts Play In Freezinmentioning

confidence: 99%

Ligation of the hairpin ribozyme in cis induced by freezing and dehydration

Kazakov¹,

Balatskaya²,

Johnston³

2006

RNA

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Although reducing the temperature slows most chemical reactions, freezing can stimulate some reactions by mechanisms that are only partially understood. Here we show that freezing stimulates the self-ligation (circularization) of linear forms of the hairpin ribozyme (HPR) containing 2¢,3¢-cyclic phosphate and 5¢-OH termini. Divalent metal ions (M 2+ ) are not required, but monovalent cations and anions at millimolar concentrations can have various effects on this reaction depending on the specific ion. Under optimal conditions, the observed rate of M 2+ -independent self-ligation reaches a peak (0.04 minC with a yield of~60% after 1 h. In contrast, no ligation occurs either at above 0 C or in solutions that remain unfrozen when supercooled to subzero temperatures. Under freezing conditions, the cleavage-ligation equilibrium strongly favors ligation. Besides freezing, evaporation of the aqueous solvent as well as the presence of ethanol at levels of 40% or above can also induce M 2+ -independent HPR ligation at 25 C. We argue that partial RNA dehydration, which is a common feature of freezing, evaporation, and the presence of ethanol, is a key factor supporting HPR ligation activity at both above-and below-freezing temperatures. In the context of the RNA world hypothesis, freezing-induced ligation is an attractive mechanism by which complex RNAs could have evolved under conditions in which RNA was relatively protected against degradation.

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“…The final system characteristics, such as the volume of the eutectic phase, will depend on the rate of cooling, final temperature and initial solute concentration. Dilute or concentrated starting solutions always reach the same molal concentration with respect to an individual solute, which is determined by the final incubation temperature [31]. An initially dilute solution will therefore form a larger amount of ice than a concentrated one.…”

Section: Eutectic Phase In Water-ice Latticesmentioning

confidence: 99%

Catalysis in abiotic structured media: an approach to selective synthesis of biopolymers

Monnard

2005

CMLS, Cell. Mol. Life Sci.

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Micro- and nanoenvironments formed by amphiphile self-assembled structures, water-ice lattices and minerals have well-defined, repeating, chemical and physical properties that can be used for selective synthesis of biopolymers, such as RNAs and proteins. The advances made in the development of polymerization supported by these micro- and nanosystems are reviewed here. In particular, it is shown that these systems promote non-enzymatic biopolymerization, yielding long polymers whose sequence composition is determined by the interactions between monomers and the supporting environment. When used to compartmentalize enzymatic biopolymerization, micro- and nanostructures allow the implementation of molecular selection and evolution schemes, which are difficult in homogeneous medium, yielding very active molecules. Thus, micro- and nanoenvironment approaches to the synthesis and selection of biopolymers could be developed into a new biotechnological tool for the production of biopolymers with novel functions.

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Cryo-bioorganic chemistry: molecular interactions at low temperature

Cited by 28 publications

References 89 publications

Ice as a protocellular medium for RNA replication

Ice as a protocellular medium for RNA replication

Ligation of the hairpin ribozyme in cis induced by freezing and dehydration

Catalysis in abiotic structured media: an approach to selective synthesis of biopolymers

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