Nep formation

The enhancement of NEP formation in the presence of sorbent materials illustrated in Figure 3 may be caused by one or botii of two factors i.e., mitigation of enzyme inactivation in the presence of sorbent materials, and/or cross-coupling of phenol to the sorbent materials. We previously demonstrated that the HRP inactivation effected by phenoxy radical attack is mitigated significantly in the presence of lignin (24), but no such enzyme inactivation mitigation occurs with the relatively hydrophobic PMS. Therefore, in the case... 

Radical-radical coupling is a second-order process by nature, thus the rate ejq>ression for NEP formation via radical self-cotq>ling reactions can be written... 

In HRP-mediated reaction systems containing a reactive sorbent, NEP is formed by phenoxy radicals via two pathways according to the process relationships schematicized in Figure 2 (i) self-coiqiling, and (ii) cross-coiqiling to sorbent materials. Total NEP formation under these conditions is given by... 

We demonstrated earlier that NEP formation by self-coiqiling is linearly correlated with initial enzyme concentration as long as sufficient substrates are siqiplied and the enzyme activity is depleted by the reaction (eq 6). The relationship between cross-coiqiling and enzyme consunqition can be analyzed in a manner similar to that enqiloyed for self-coupling. We first substituted die radical concentration in eq 8 above with the proportionality relationsh (eq 1)... 

Equation 12 indicates that NEP formation via cross-coupling reactions, NEP c, correlates with the logarithm of ( ]o. 

Equations 7, 6 and 12 together provide a conq>lete description of the quantitative relationships involved in HRP-mediated phenol coiq>ling in s3 tems containing reactive sorbents. As stated in eq 7, the total NEP formation... 

Figure 4, NEP formations at varied HRP dosage in a system containing 25-g/L PMS (A) and OJ-g/L lignin (B), Initial phenol concentration = 500 pM, initial H2O2 concentration = 2 mM, reaction time - 2 h. Data points are the means of triplicate experiments with I SD error bars. Dashed lines represent predictions of eq 6, and solid lines simulations of eq 12,...

Vasopeptidase inhibitors are a new class of cardiovascular drugs that inhibit two metalloprotease enzymes, NEP 24.11 and ACE. They thus simultaneously increase the levels of natriuretic peptides and decrease the formation of Ang II. As a result, they enhance vasodilation, reduce vasoconstriction, and increase sodium excretion, in turn reducing peripheral vascular resistance and blood pressure. 

Studies of peptidase inhibitors in brain slices indicate the importance of inhibiting both enzymes in order to significantly increase the concentrations of the endogenous opioid peptides (see Refs. 973-976). Thus, inhibiting NEP with thiorphan decreases the formation of [ H]Tyr-Gly-Gly from [ H]Met-enkephalin, but increases the production of [ H]Tyr, whereas the opposite results were found with the APN inhibitor bestatin. Both APN and NEP, as well as the other enzymes involved in enkephalin metabolism, are zinc metallopep-tidases. Thus it is possible to design mixed inhibitors capable of blocking multiple enzymes that more effectively protect the opioid peptides from metabolism (see below). 

The formation of deoxyosones, such as, for example, the 3-deoxyosones, appears to be the most important of the dehydration reactions which may take place during Lobry de Bruyn-Alberda van Ekenstein transformations. This type of reaction, which NeP first proposed in suggesting mechanisms for saccharinic acid formation, is difficult to study because the products are seldom stable in the reaction mixtures in which they are formed. Nevertheless, several different lines of evidence now indicate that reducing sugars undergo primary dehydrations of this kind, and that deoxyosones do indeed mediate in saccharinic acid formation in basic solutions, as well as in production of 2-furaldehyde and its derivatives in acidic media. 

The membranes of the two vesicle populations, and possibly others, form the double membrane of the NE, which must be continuous around the chromatin before the nascent nuclei are able to accumulate imported proteins. Our results indicate that the fusion of NEP-A vesicles with NEP-B vesicles is necessary for the formation of a functional NE, but we have not yet defined the precise contribution(s) of either vesicle population to the fully assembled NE. Proteins in both vesicle populations may be required for the fusion of inner and outer nuclear membranes at the sites of NPC assembly, and for the recruitment of the disassembled subunits of NPCs to the nascent NE. While the recruitment of NPC subunits to the NE membrane could either precede or follow the fusion of inner and outer membranes, some NPC proteins almost certainly associate with the NE after the fusion of inner and outer nuclear membranes. Finlay and Forbes (1990) have shown that the depletion of a subset of NPC proteins using wheat germ agglutinin-conjugated agarose resulted in the assembly of NEs in which inner and outer membranes had fused, but which were unable to import proteins. 

---