Polynucleotide phosphorylase PNPase

Synthetic oligonucleotides may be used as "primers and be elongated stepwise with the aid of polynucleotide phosphorylase (PNPase) and nucleoside diphosphates. 

After more than 20 years, Walde et al. (1994) returned in a way to coacervate experiments, although using other methods. Walde (from the Luisi group) repeated nucleotide polymerisation of ADP to give polyadenylic acid, catalysed by polynucleotide phosphorylase (PNPase). But instead of Oparin s coacervates, the Zurich group used micelles and self-forming vesicles. They were able to demonstrate that enzyme-catalysed reactions can take place in these molecular structures, which can thus serve as protocell models. Two different supramolecular systems were used ... 

The experiments were carried out using Ci4-phosphatidylcholine (PC) vesicles. The biochemical reaction which was planned to occur in the vesicles was the aforementioned RNA polymerisation reaction involving the enzyme polynucleotide phosphorylase (PNPase), which Oparin and co-workers had used many years ago in their work on coacervates. PNPase and added ADP then form oligonucleotides in the vesicles. 

Polynucleotide Phosphorylase Origin Bacillus stearothermophilus Unitika Polynucleotide Phosphorylase (PNPase)... 

Oparin and coworkers [125,126] have studied the enzymic polymerization of ADP by polynucleotide phosphorylase (PNPase) and Mg ions in coacervates in an attempt to construct primitive forms of precellular structures. Walde et al. [127] have investigated this enzymic ADP polymerization in AOT reversed micellar solutions instead of coacervates. The PNPase-catalyzed synthesis of poly(A) (polyadenylic acid) in the AOT reversed micelles was carried out by mixing two reversed micellar solutions, one containing ADP and the other containing the enzyme. 

Key words Poly(adenylic acid) (poly(A)) - sodium bis(2-ethylhexyl) sulfosuccinate reversed micelle -liquid/solid interface -polynucleotide phosphorylase (PNPase) - atomic force microscopy (AFM)... 

We have studied the enzymatic polymerization of ADP in a sodium bis(2-ethylhexyl) sulfosuccinate, AOT, reversed micellar system [3]. This enzymatic polymerization by polynucleotide phosphorylase(PNPase) and Mg ion was greatly different from the general aspect of the enzy-... 

Snake venom phosphodiesterase and polynucleotide phos-phorylase. Snake venom diesterase is an exonuclease that hydrolyzes both DNA and RNA it can be isolated from the venom of many poisonous snakes. It attacks sequentially from the 3 -OH end and yields 5 -phosphates. Polynucleotide phosphorylase (PNPase) has a similar mode of action. As the name indicates, it is a phosphorylase and not a... 

Limited attack by nucleases at 0° shows that certain regions of tRNA are still accessible. PNPase (Chapter 3, Section 3.4.2, p. 27) acts sequentially on the 3 OH end of unstructured polynucleotides. But tRNA is only slightly affected by polynucleotide phosphorylase (18), and the decrease in acylation capacity parallels the extent of phosphorolysis. This indicates that some of the tRNA molecules are not attacked at all (since they still accept amino acids) and that the molecules attacked by the enzyme are completely degraded. Therefore, the -C-C-A terminus must be protected. Heating increases the enzymatic availability of the... 

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