Cleavage poly phosphate

Poly(L-malate) decomposes spontaneously to L-ma-late by ester hydrolysis [2,4,5]. Hydrolytic degradation of the polymer sodium salt at pH 7.0 and 37°C results in a random cleavage of the polymer, the molecular mass decreasing by 50% after a period of 10 h [2]. The rate of hydrolysis is accelerated in acidic and alkaline solutions. This was first noted by changes in the activity of the polymer to inhibit DNA polymerase a of P. polycephalum [4]. The explanation of this phenomenon was that the degradation was slowest between pH 5-9 (Fig. 2) as would be expected if it were acid/base-catalyzed. In choosing a buffer, one should be aware of specific buffer catalysis. We found that the polymer was more stable in phosphate buffer than in Tris/HCl-buffer. 

This enzyme [EC 3.1.26.6], also known as endoribo-nuclease IV and poly(A)-specific ribonuclease, catalyzes the endonucleolytic cleavage of poly(A) to fragments terminated by 3 -hydroxyl and 5 -phosphate groups. Oligonucleotides are formed with an average chain length of ten. 

Fig. 4.42. Cleavage of a poly[(/J-cyanoethyl)phosphate] according to the Elcb mechanism.

PS-fc-poly(4-f-butylstyrene)]n, (PS-fi-PfBuS) star-block copolymers were prepared by anionic polymerization and sequential addition of monomers with DVB as the linking agent for the formation of the star structure [156]. The functionality of the stars ranged between 10 and 20. Selective sulfonation of PS blocks was subsequently performed using the sulphur trioxide and triethyl phosphate complex in 1,2-dichloroethane, followed by neutralization with sodium methoxide. For this reason DVB was used for the linking reaction instead of chlorosilanes, where a better control could be achieved. DVB stars are more robust and the sulfonation reaction proceeds without cleavage of the arms from the star structure. 

Mobilization, in which poly-, oligo- and disaccharides are cleaved and phosphorylated to hexose phosphates, particularly to glucose 6-phosphate. In digestion, cleavage occurs by hydrolysis. 

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