Cross reactions/reactivity

The second step introduces the side chain group by nucleophilic displacement of the bromide (as a resin-bound a-bromoacetamide) with an excess of primary amine. Because there is such diversity in reactivity among candidate amine submonomers, high concentrations of the amine are typically used ( l-2 M) in a polar aprotic solvent (e.g. DMSO, NMP or DMF). This 8 2 reaction is really a mono-alkylation of a primary amine, a reaction that is typically complicated by over-alkylation when amines are alkylated with halides in solution. However, since the reactive bromoacetamide is immobilized to the solid support, any over-alkyla-tion side-products would be the result of a cross-reaction with another immobilized oligomer (slow) in preference to reaction with an amine in solution at high concentration (fast). Thus, in the sub-monomer method, the solid phase serves not only to enable a rapid reaction work-up, but also to isolate reactive sites from... 

A variety of hydrophobic and hydrophilic squaraine rotaxane probes and labels such as 21a-21e c Rp and 22a-22e c Rp, containing reactive carboxylic functionalities and hydrophilic sulfo groups, are disclosed in a recent patent application [60]. It was shown that not only aniline-based squaraines 21a-21e but also heterocyclic squaraines 22a-22e can form stable pseudorotaxane complexes. The indo-lenine-based squaraine 22a forms rotaxane 22a C Rp. Importantly, also the sulfonated squaraine 22b could be successfully encapsulated in a Leigh-type, phenylene-based, tetralactam macrocycle to yield the water-soluble rotaxane 22b C Rp. Quatemized, indolenme-based squaraines do not form pseudorotaxanes probably because of sterical hindrance caused by /V-alkyl and 3,3 -dimethyl groups. On the other hand, quatemized benzothiazole (22c) and benzoselenazole (22d) squaraines could be embedded in a Leigh-type macrocycle to yield rotaxanes 22c C Rp and 22d C Rp, respectively. The hydrophilic, mono-reactive rotaxane 22e-NHS C Rp based on asymmetric squaraine, synthesized by a cross-reaction of squaric acid with the two different indolenines, was also obtained. 

Some patients will have repeatedly nonspecific reactivity in an ELISA assay, since the HIV-1 antigen used for the antibody assays is produced in cultured human T cells. It is not unexpected that occasional false positive assays occur in human sera from individuals with autoimmune diseases a history of multiple pregnancies or multiple transfusions or antibodies to certain class II histocompatibility antigens (especially HLA-DR4). Block reagents have been added to specimen diluents to minimize cross-reactions in these sera. This necessitates the use of confirmatory tests, especially the Western blot. With the use of both ELISA and Western blots, false positives decrease to less than 1 per 100,000. 

Application of the RIA. The RIA was initially used to evaluate the cross-reaction of the STXOL antisera to STX. The antibody was found to have excellent STX cross-reactivity (93%). Subsequent preparation of a logit/log (37) standard curve for STX (Figure 4) demonstrated that the chosen assay format would give good reproducibility and a desirable order of magnitude linear sensitivity range. 

Cross-reactivity between molluscan and crustacean shellfish species also occurs rafher frequently. Since tropomyosin is the major allergen in both molluscan and crustacean shellfish, fhe frequency of cross-reactions is not surprising. Allergy to crustacean shellfish is more frequenfly diagnosed than molluscan shellfish allergy (Hefle et ah, 2007). Many of fhese individuals may be at risk of reactions fo molluscan shellfish also. Appropriately, most individuals with either molluscan or crustacean shellfish allergy are advised to avoid all shellfish. 

Cross-reaction with other BAs was undetectable However, cholesterol exhibited a cross-reactivity of 5.6%, and for this reason the separation step by TLC was introduced. 

Heidelberger and Aisenberg240 studied the cross-reaction of the Merck and DuPont polyglucoses with antibodies to pneumococcal C-substance and to type-specific polysaccharides. One of the D-glucose polymers (Merck 52R61I) was separated into a series of fractions on the basis of fractionation with alcohol (isopropyl alcohol and ethanol) and with glacial acetic acid, the most insoluble fraction being called A, and the most soluble, E. The yield, analyses, and reactivity of these fractions with Types IX, XII, XX, and XXII antipneumococcal horse sera are presented in Table VII. 

We now explore whether the pattern of reactivity predicted by the Marcus theory is found for methyl transfer reactions in water. We use equation (29) to calculate values of G from the experimental data where, from (27), G = j(JGlx + AG Y). The values of G should then be made up of a contribution from the symmetrical reaction for the nucleophile X and for the leaving group Y. We then examine whether the values of G 29) calculated for the cross reactions from (29) agree with the values of G(27) calculated from (27) using a set of values for the symmetrical reactions. The problem is similar to the proof of Kohlrausch s law of limiting ionic conductances. 

IgE antigens combined with in vitro tests of cross-reactions of IgE and sequenced antigens, as it has been found that the basic condition for positive cross-reactivity is the high structural compatibility (homology) of reagents. Compared to B-cells, T-cell cross-reactivity is far more difficult to assess because the mechanism of T-cell effects is more diverse and involves both the phase of immunological response and the effect phase of the allergic reaction. 

Several authors report coexisting clinical soy allergies in 5%-50% of patients with cows milk allergies (NDA Opinion 2004). It is unclear whether soy allergy represents a de novo sensitization or a cross-reaction of a soy protein component with caseins from milk (Rozenfeld et al. 2002). However, due to homology in the amino acid sequences of soybean and cow s milk allergens of 50%-70%, cross-reactivity is likely (Wilson et al. 2005). 

Immunoassays for Bik, based on polyclonal antibodies (pAb), are affected by cross-reaction with Tamm-Horsfall protein (THP). This problem can lead to the generation of false positive results in cases of proteinuria [14], In contrast, immunoassays that utilize plasma suffer from cross-reactivity to Iof [23]. The cross-reactivity with THP is due to complexed N-linked glycan, whereas cross-reactivity with Iof is due to bound Bik [14]. Cross-reaction with a-1-glycoprotein (AGP) also does not appear to be a significant factor in blood. 

Tissue cross-reactivity (TCR) studies Tissue cross-reactivity studies with human tissues (or cells if applicable) are conducted prior to Phase 1 to search for cross-reactions with the intended target and/or nontarget tissue. In special cases of bispecific antibodies, each parent antibody is evaluated individually in addition to testing the bispecific product. Human cells or tissues are surveyed immunocyto-chemically or immunohistochemically with appropriate controls. Animal species are also surveyed to determine relevant species for toxicology studies. 

The results of kinetic studies of the reduction of stellacyanin, plastocyanin, and azurin by Fe(EDTA)2" are summarized in Table III (20, 21). The order of cross reaction rate constants (ki2 values) is stellacyanin > plastocyanin > azurin, which is surprising, as considerations based on driving force alone would predict stellacyanin to be the least reactive of... 

Based on the Fe(EDTA)2- results, the blue copper center in stellacyanin appears to be much more accessible than that situated in either azurin or plastocyanin. Thus it should be profitable to compare the electron transfer reactivities of these three proteins with a variety of redox agents. Kinetic studies of the oxidation of the three blue proteins by Co(phen)33+ have been made (26), and the results together with those for other redox agents are set out in Table IV. The electrostatic corrections to the predicted kn values are modest both for the large charge on plastocyanin and the small one on azurin, as the protein selfexchange and the cross reaction work terms compensate. The reactivity... 

The reactivity of peroxy radicals towards other peroxy radicals varies over many orders of magnitude depending on the nature of the R group. Consequently, it is not possible to provide a simple accounting of the importance of peroxy self and cross reactions compared to the other possible loss mech-... 

Antibodies to one protein antigen will often react (cross-react) with a wide variety of similar proteins from other species. For example, 15% of the antibody in a polyclonal antiserum to bovine serum albumin will react with human serum albumin. The molecular basis for this cross-reaction is not clearly understood, but cross-reactivity is believed to be caused by the presence of a configuration of amino acid side chains on another protein molecule that has a sufficient overall similarity to the specific configuration on the original antigen that induced antibody formation. 

---