Conjugated process

The halogen substituents ( — 7 +M) owe their o p-orientating effect, achieved in spite of the deactivation, to polarisability by the conjugative process. The strength of the inductive deactivation is seen in the sequence of the two ratios quoted. 

Bhadra R, DG Wayment, JB Hughes, V Shanks (1999) Confirmation of conjugation processes during TNT metabolism by axenic plant roots. Environ Sci Technol 33 446-452. 

In two-step protocols, one of the proteins to be conjugated is reacted with the homobifunctional reagent and excess crosslinker and by-products are removed. In the second stage, the activated protein is mixed with the other protein or molecule to be conjugated, and the final conjugation process occurs (Figure 4.2). 

In some cases, the ability to modify glycans at the reducing end without reduction preserves the carbohydrate s native structure sufficiently to allow interactions with proteins that would otherwise not interact if the bond were reduced. Therefore, depending on the ultimate use of the biotinylated carbohydrate, using a hydrazide mediated conjugation process can have advantages over the use of amine-biotin compounds. 

Other investigators, however, have demonstrated that conjugations of antibody with intact, two-subunit toxins can be done using non-cleavable crosslinkers such as NHS ester-maleimide heterobifunctionals (Chapter 5, Section 1) (Myers et al., 1989). Presumably, the toxin is still able to release the A chain after the antibody has bound to the cell, since the conjugation process does not permanently attach the two toxin subunits together—only the toxin to the antibody. 

A-chain immunotoxins, however, may not be quite as cytotoxic as conjugates formed from intact toxin molecules (Manske et al., 1989). In an alternative approach to A chain use, the intact toxin of two-subunit proteins is directly conjugated to a monoclonal without isolation of the A chain. Conjugation of an antibody with intact A-B chain toxins can be done without a cleavable linker, as long as the A chain can still separate from the B chain once it is internalized. Therefore, it is important to avoid intramolecular crosslinking during the conjugation process which can prevent release of the A-B complex. In addition, since the B chain... 

The conjugation process must leave the antigen binding sites on the antibody component free to interact with its intended target. Crosslinker modification or blockage of these binding sites by the attached toxin must be kept to a minimum. 

The two-step nature of SPDP crosslinking provides control over the conjugation process. Complexes of defined composition can be constructed by adjusting the ratio of enzyme to secondary molecule in the reaction as well as the amount of SPDP used in the initial activation. The use of SPDP in conjugation applications is extensively cited in the literature, perhaps making it one of the more popular crosslinkers available. It is commonly used to form immunoto-xins, antibody-enzyme conjugates, and enzyme-labeled DNA probes. A standard activation and coupling procedure can be found in Chapter 5, Section 1.1. 

UBP43 mouse accumulation of IsglS conjugates processes IsglS, regulates IsglS conjugate levels [31]... 

The activity of j8-glucuronidase at the usual pH of the transferase assays (pH 7.4r-8.2) is very low. The enzyme, most likely, has no role in the conjugation process itself (G4). If potentially important, e.g., in work with homogenates or cell extracts containing partially lysed lysosomes, the specific inhibitor saccharo-(l4)-lactone (L9) can be added to the incubation mixtures. 

Two types of enzymatic pathways, the so-called phase I and phase II pathways, are generally implicated in drug biotransformation. Phase I pathways correspond to functionalization processes, whereas phase II correspond to biosynthetic or conjugative processes. Phase I functionalization processes include oxidation, reduction, hydrolysis, hydration, and isomerization reactions. 

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