Enzymatic reactivity

On the other hand, the macrolides showed unusual enzymatic reactivity. Lipase PF-catalyzed polymerization of the macrolides proceeded much faster than that of 8-CL. The lipase-catalyzed polymerizability of lactones was quantitatively evaluated by Michaelis-Menten kinetics. For all monomers, linearity was observed in the Hanes-Woolf plot, indicating that the polymerization followed Michaehs-Menten kinetics. The V, (iaotone) and K,ax(iaotone)/ m(iaotone) values increased with the ring size of lactone, whereas the A (iactone) values scarcely changed. These data imply that the enzymatic polymerizability increased as a function of the ring size, and the large enzymatic polymerizability is governed mainly by the reachon rate hut not to the binding abilities, i.e., the reaction process of... 

PPL catalyzed polycondensation of bis(2,2,2-trichloroethyl) alkanediaoates with glycols in anhydrous solvents of low polarity to produce the polyesters [34, 35]. In the polymerization of bis(2-chloroethyl) succinate and 1,4-butanediol using Pseudomonas fluorescens lipase (lipase PF) as catalyst, the polyester with low molecular weight was formed [36]. This may be due to the low enzymatic reactivity of the succinate substrate. 

While PAL itself is recovered from the soluble fractions of cellular lysates via ultracentrifugation purifications, strong experimental evidence suggests it exists as part of a multienzyme complex associated with the endoplasmic reticulum (ER), forming a metabolic channel tunneling substrates directly from one enzymatic reactive site to another (Winkel 2004). The enzyme physically anchored to the ER is cinnamate... 

It has been said that inositol is a sugar with carbon in the ring. Indeed it is interesting to reflect on the effect of such a simple atom-for-atom replacement on the chemical anc enzymatic reactivities of a hexose, when compared with a rather inert cyclitol. 

Chang, V. S., and Holtzapple, M. T., 2000, Fundamental factors affecting biomass enzymatic reactivity, Appl. Biochem. Biotechnol. 84 5-37. 

The system may be regarded as involving a Na+/Mg2+ co-catalysed phosphorylation step and a K+ catalysed dephosphorylation. Each phosphorylation/dephosphorylation step involves a pseudorotation of an Mg2+-stabilised 5-coordinate intermediate, resulting in transport of the alkali metal cations. The cation transport ability of the enzyme is a direct result of the enzymatic reactivity of the protein. There are three binding sites with high Na+ affinity and two with K+ affinity (occupied by Rb+ in the crystal structure determination). The structure (which is of the E2K state of the system) reveals that carboxy end of the a-subunit is held in a pocket in between transmembrane helices and acts as an unusual regulating element that controls sodium affinity and may be influenced by the membrane potential. 

The quantities KM and Vmmdite important parameters that can be used to characterise and understand enzymatic reactivity. The Ku value is the Michaelis constant which is defined as the substrate concentration at which the reaction rate is half of its maximal value. Hence KM (which varies considerably) is... 

N-substituted iron porphyrins form upon treatment of heme enzymes with many xenobiotics. The formation of these modified hemes is directly related to the mechanism of their enzymatic reactivity. N-alkyl porphyrins may be formed from organometallic iron porphyrin complexes, PFe-R (a-alkyl, o-aryl) or PFe = CR2 (carbene). They are also formed via a branching in the reaction path used in the epoxidation of alkenes. Biomimetic N-alkyl porphyrins are competent catalysts for the epoxidation of olefins, and it has been shown that iron N-alkylporphyrins can form highly oxidized species such as an iron(IV) ferryl, (N-R P)Fe v=0, and porphyrin ir-radicals at the iron(III) or iron(IV) level of metal oxidation. The N-alkylation reaction has been used as a low resolution probe of heme protein active site structure. Modified porphyrins may be used as synthetic catalysts and as models for nonheme and noniron metalloenzymes. 

Quantum-chemical molecular descriptors have been actively used in the quantitative structure-activity relationship studies of biological activities [1,2,72]. In the following, examples of QSARs involving quantum-chemical descriptors and applied on the enzymatic reactivity, pharmacological activity, and toxicity of compounds are discussed. 

Nevertheless and as further detailed in Ref. [3], the series of p values calculated from enzymatic reactivities for a series of alcohols is reasonable for 8% of C12EO23 in the ternary system it is 0.5, 0.6, 0.9, and again 0.9, from 1-butanol to 1-heptanol, respectively. And for 22% of surfactant the series from ethanol to 1-octanol shows the following values 0.0, 0.0, 0.8, 0.7, 0.9,1, and 1. Except for 1-butanol, this result also makes sense. 

As a conclusion of this part we can state that enzymatic reactivity is a very sensitive measure of (1) stractural changes, (2) completion of hydration (of surfactant and cosurfactant), (3) partitioning of the various components, (4) interfacial film rigidity, and, not to forget, (5) pH. 

Many dicarboxylic acids are commercially available however, their enzymatic reactivity is relatively low. Mucor miehei lipase (lipase MM) in immobilized form induced the polycondensation of adipic acid and 1,4-butanediol in diisopropyl ether [29]. A horizontal two-chamber reactor was employed to... 

Swiderek K, Tunon 1, Moliner V (2014) Predicting enzymatic reactivity from theory to design. Wires Comput Mol Sci 4(5) 407-421... 

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