Enzymatic stability

Synthesis and enzymatic stability of oligonucleotides consisting of isonucleosides 99PAC1143. 

R. T., Acyloxyalkoxy-based cyclic prodrugs of opioid peptides evaluation of their chemical and enzymatic stability as well as their transport properties across Caco-2 cell mono-layers, Pharm. Res., 1999, 36, 24-29. 

It should not jeopardize the quality of the enzyme formulation itself (physical, microbial and enzymatic stability etc.)... 

Endothelial permeability Transporter proteins Enzymatic/metabolic activity Disease Tissue composition (drug sequestration) Dose size/volume Conformation Chemical stability Enzymatic stability... 

Peptides can be chemically transformed on insoluble supports to yield other types of oligomer. These transformations include N-alkylation and reduction. N-Alkylation of polystyrene-bound peptides enables the preparation of peptide mimetics with improved enzymatic stability [270], Polyamines have been prepared by exhaustive reduction of peptides with borane [271] (see Section 10.1.6). N-Alkylated polyamines can be prepared on solid phase by reduction of the corresponding N-alkylated peptides [272]. 

Using the optimum extraction conditions described above (Polyclar SB-100), the enzyme activity of the crude extract did not vary for at least 5 months when the extract was stored in a refrigerator at 4°C. Cysteine plus Amberlite CG-400 ion-exchange resin also provided a good enzymatic stabilization, but not cysteine alone, as can be seen in Fig. 17.2. 

In several other instances, a direct relationship between the reaction outcome and pressure was not observed. In two cases, an optimum was found for the reaction rate (Ikushima et al., 1996 Yoon et al., 1996). As was the case for the effects of temperature, while many of the products became more soluble as pressure increases, sometimes the enzyme activity and stability are adversely affected by the increased pressure. Examples of enzymatic stabilities at various reaction conditions may be seen in Table 6.2. 

Table 6.2. Examples of Enzymatic Stability in Carbon Dioxide... 

The unique chemistry was adapted to use in combinatorial synthesis and was complemented by in silico technologies for the rational design of libraries, in order to optimize diversity of building blocks, obtain molecules with remarkable enzymatic stability, but also to get information from analysis of i.e. conformational constrains, molecular rigidity, size, charge, and hydrophobicity. 

The first step for the design of an EMR is to select the type of reactor. Extractive membrane reactors are desirable when one of the substrates or products is poorly soluble in aqueous solution or when an undesirable by-product has to be separated, as the membrane acts as a solvent extraction step [99]. Immobilized enzyme reactors are usually applied with materials that enable enhancement of enzymatic stability or preserve enzyme from deactivation by a direct contact with an organic solvent [99]. Finally, direct-contact membrane reactors are the most versatile alternative in processes with soluble compounds. 

Different industries pose different challenges to the protein formulator. Many feed enzymes are sold as formulated liquid concentrates. In this case, the major requirements for a liquid formulation are enzymatic stability and preservation against microbial growth. It is sometimes not appreciated that the dominant factor affecting enzyme stability is the intrinsic stability of the enzyme itself formulation can do very little to correct for a structurally labile protein. Therefore, it is advisable to make stability an important criterion of the initial enzyme screening process. 

Manea, M., Horvati, K., Mezo, G., Cecal, R., Tian, X., Stefanescu, R., Hudecz, F. and Przybylski, M. (2004) Synthesis, antibody recognition and enzymatic stability of linear, cyclic and... 

To increase the enzymatic stability of oligotuftsin, N-terminal acetylation was applied in further experiments. Branching on Lys residues next to Gly residues increased the stability of the Lys-Gly bond in tryptic digestion. 

Use of formulation techniques can improve the bioavailability and/or minimize the toxicity and side effects of drugs. Factors to consider include those that impact on solubility and dissolution rates, chemical and enzymatic stability, and absorption capability. 

As shown the thickness of these nanosheets is about 20 nm. There are numerous nanoscaled cavities on the surface of ZnO microspheres. The size of the cavity is about several hundred nanometers, which is accessible for the enzymes to sequester in the cavities or bind on the surface. Furthermore the cavities may provide a protective microenvironment for the enzymes to retain their enzymatic stability and activity by limiting the conformational change and unfolding of the entrapped enzyme. The FTIR spectra of hemoglobine (Hb) and Hb-ZnO- nafion composite film is shown in Fig.4B. The similarities of two spectra suggested that Hb retained the essential features of its native secondary structure in ZnO nafion composite film, and revealed the excellent biocompability of ZnO nafion composite film. Cyclic voltammetry response of the biosensor at different scan rates was shown in Fig.5. 

This simple approach neglects the influence of geometrical differences in the phosphoryl group in the ground state and transition state, which have been shown to have the potential to result in preferential enzymatic stabilization of a loose, metaphosphate-like transition state.26,27 While there have been many reports of the accelerating effect of metal ions on phosphoester hydrolysis,28 31 few of these reactions have been studied mechanistically to ascertain how the transition state for phosphoryl transfer might have been affected. 

Therefore, the inclusion of an electron donating group such as the amino group has greatly increased the chemical and enzymatic stability of our cholinergic agonist. Unfortunately, it is found that carbachol shows very little selectivity between the muscarinic and nicotinic sites. 

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