Latent chemical activation

The elimination or inactivation of enzymes used to treat proteins is a critical problem once the desired modification in functionality is achieved. In many instances, product inhibition or self destruction does not occur as noted above for fish protein concentrate. As stated by Puski (20), if heat inactivation is used, the proteins may be denatureT"and revert to insoluble forms. Washing out the enzyme at its isoelectric point would also remove a portion of the protein which is solubilized by the enzyme. Inactivation of enzymes by chemical means may also cause significant changes in the protein. Thus, while desired functional modifications of food ingredients may be obtained through enzyme treatment, the problem of latent enzyme activity in food formulations must be addressed. 

As with the Basic Protocol, this method can be used to assess latent DPO activity by addition of SDS. This simple assay system may also be used to investigate the effect of DPO inhibitors by adding suitable quantities of test compound dissolved in buffer (Ferrar and Walker, 1996, 1999). However, it must be remembered that, in this assay system, the prevention of color development (enzymic browning) may be due to chemical reactions between the inhibitor and the reaction products preventing the formation of the colored end-product, rather than the actual inhibition of the enzyme. This problem may be avoided by use of the 02-electrode assay (see Basic Protocol). 

As indicated above, bioprecursor prodrugs do not contain a carrier or promoiety but rather contain a latent functionality that is metabolically or chemically transformed to the active drug molecule. The types of activation often involve oxidative activation, reductive activation, phosphorylation, and in some cases chemical activation. Of these, oxidation is commonly. seen, since a number of endogenous enzymes can carry out these transformations. Phosphorylation has been widely exploited in the development of antiviral agents, and many currently available agents depend on this type of activation. 

The committee s analyses of past chemical events at Johnston Atoll Chemical Agent Disposal System (JACADS) and Tooele Chemical Disposal Facility (TOCDF) indicate that the cansal factors are similar to those associated with breakdowns of other safety-critical systems. Release of chemical agent may be triggered by equipment design flaws and failures, by procedural deficiencies, and by human actions—i.e., by both latent and active failures (see Chapter 2). 

Other monohydric alcohols listed in Tables 1.1-1 A but not mentioned thus far are used as chemical intermediates to prepare specialty ester and amine derivatives. These solvents may be latent or active solvents in certain adhesive, coating, or lacquer formulations or act as an extraction solvent. The desired evaporation rate of the adhesive or coating formulation will often determine which alcohol is selected. 

A widely used strategy for latent catalyst activation is the addition of a chemical entity or a co-catalyst to promote the formation of the active species. Co-catalysts are usually a carbene source (such as diazo compounds) or an acidic compound (Bronsted or Lewis) that stimulates the dissociation of hgands from the ruthenium complex to generate an active species. 

Since September 1997, the Journal of Chemical Education (JCE) publishes on a regular base a Classroom Activity that is set separately on a distinct hard sheet, including both the student activity (on one side) and instructor information sheet (on the back side). These activities are designed to actively engage students, while the topics covered are usually coimected with everyday life and apphcations (e.g. acid rain, bath bubblers, toothpastes, water filtration, anthocyanins, latent fingerprints, etc.). Liapi and Tsaparlis (2007) have used three of these activities (acid rain, bath bubblers, toothpastes) in conjunction with two conventional laboratory activities (some properties of acids/some properties of bases) with a class of ninth-grade students in Greece. An evaluation by the students showed a very positive result in favour of the JCE Activities they are connected with life and involve creativity on the part of the students (Fig. 5.2). 

SPECIFIC ACTIVITY TURNOVER NUMBER OPTICAL ACTIVITY ACTIVITY COEFFICIENT CHEMICAL POTENTIAL FUGACITY LATENT ACTIVITY BIOMINERALIZATION ACTIVITY COEFFICIENT ACTIVITY... 

One of the more common pathways for the metabolic transformation of tertiary amines involves A -dealkylation to a secondary amine. The observation that those products often show the same biological activity as the parent dmg in many cases confounds the issue of the identity of the chemical species responsible for the drug s action. The fact that the dealkylation product of disobutamide shows antiarrhythmic activity in its own right prompted the synthesis of the acetyl derivative of that secondary amine this agent may be considered a latent form of the active metabohte. This compound is prepared by first repeating the penultimate step in the disobutamide synthesis using (Af-benzyl-Af-isopropyl)-2-chloroethylamine instead of the diisopropyl intermediate. The product from that reaction (56-1) is then hydrolyzed to the... 

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