Hydrolysis cleavage

In complex 8, also prepared by Czamik and coworkers [34], the two (cyclen)Co(III) units are linked by a different spacer. Models predicted that the complex is prohibited from forming an intramolecular ji-hydroxo dimer. Furthermore, the mononuclear subunits are more rigidly held compared with complex 6. Whereas no rate increase over 7 is achieved for BNPP hydrolysis, cleavage of the monoester NPP by 8 is 10 times faster than by (cyclen)Co in twofold concentration. 31P NMR data indicate that a four-membered chelate may be involved in the cleavage mechanism, as observed in the case of 5. 

The study of posttranscriptional processing of RNA molecules led to one of the most exciting discoveries in modern biochemistry—the existence of RNA enzymes. The best-characterized ribozymes are the self-splicing group I introns, RNase P, and the hammerhead ribozyme (discussed below). Most of the activities of these ribozymes are based on two fundamental reactions transesterification (Fig. 26-13) and phosphodiester bond hydrolysis (cleavage). The substrate for ribozymes is often an RNA molecule, and it may even be part of the ribozyme itself. When its substrate is RNA, an RNA cat-... 

From a rare fungus you have isolated an octapeptide that prevents baldness, and you wish to determine the peptide sequence. The amino acid composition is Lys(2), Asp, Tyr, Phe, Gly, Ser, Ala. Reaction of the intact peptide with FDNB yields DNP-alanine plus 2 moles of e-DNP-lysine on acid hydrolysis. Cleavage with trypsin yields peptides the compositions of which are (Lys, Ala, Ser) and (Gly, Phe, Lys), plus a dipeptide. Reaction with chymotrypsin releases free aspartic acid, a tetrapeptide with the composition (Lys, Ser, Phe, Ala), and a tripeptide the composition of which, following acid hydrolysis, is (Gly, Lys, Tyr). What is the sequence ... 

The mechanism of enzyme-catalyzed hydrolysis of glycosidic linkages is analogous to acid-catalyzed hydrolysis. Cleavage is between the glycosyl anomeric carhon (Cl) and the gly-... 

Several conclusions are drawn from the product studies of the reactions of propylene oxide and isobutylene oxide in H O.23 In the acid-catalyzed hydrolysis of propylene oxide, cleavage of the secondary C-O bond is favored by a factor of 2-3 over cleavage of the primary C-O bond. In the acid-catalyzed hydrolysis of isobutylene oxide, cleavage of the tertiary C-O bond is highly favored (>99%). These results show that in acid-catalyzed epoxide hydrolysis, cleavage of the C-O bond leading to... 

The linker is activated by the removal of the Boc-protecting group with TFA. At neutral pH the imidazole can catalyze the intramolecular hydrolysis (cleavage) of the ester bond. 

Acetonide hydrolysis—cleavage. Terminal acetonides are selectively hydrolyzed and cleaved with HjIOs. Sometimes, a one-pot reaction can be accomplished. ... 

These words are taken from the Greek homo, the same, and hetero, different and lysis, a loosing. To a chemist fysis means "cleavage as in, for example, hydrolysis, "cleavage by water".)... 

Second generation Membranes made of polymers, mainly derived from polyolefins or polyethersul-fone. They were introduced in 1975, with different chemical compositions and functional properties, such as PA and PS membranes. They are resistant to hydrolysis (cleavage of internal links of the polymer) and strong acids and bases and high temperature. However, they have a low resistance to mechanical compaction. These membranes are commonly used today. 

Several methods are available for the removal of the AT-formyl group. As an alternative to acid or alkaline hydrolysis, cleavage may be effected with sodium hydride in refluxing dimethoxy-ethane. This gives the free base together with carbon monoxide and hydrogen, probably by a concerted process [39]. An acyl exchange reaction with a hydrazine or hy oxylamine derivative may also be used [40]. 

C. Solubilization via Hydrolysis Cleavage of the Polymer Chain or Backbone. A number of chemical reactions are available to provide for solubilization of polymer backbone to yield an active pesticide. Some of these reactions are illustrated in Equations 6-9. ... 

When an acetal is treated with aqueous acid, it is expected to undergo hydrolysis. We first identify the bonds that will undergo cleavage. When an acetal undergoes hydrolysis, cleavage occurs for the C-0 bonds of the acetal group ... 

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