Homology, definition

Compounds of this type possess a definite Aj-selenazoline structure, while homologous compounds with at least one labile hydrogen on the 2-amino group can exist as a tautomeric equilibrium (Scheme 64). 

Deuteration studies with acetic acid-d4 (99.5% atom D) as the carboxylic acid building block, ruthenium(IV) oxide plus methyl iodide-d3 as catalyst couple and 1/1 (C0/H2) syngas, were less definitive (see Table III). Typical samples of propionic and butyric acid products, isolated by distillation in vacuo and glc trapping, and analyzed by NMR, indicated considerable scrambling had occurred within the time frame of the acid homologation reaction. 

In summary, it is reasonable to conclude that bioinformatic analysis of structural similarities to, or of sequence homology with, known protein allergens, and evaluation of stability with SGF, can both contribute, if interpreted cautiously, to an overall assessment of sensitizing hazard. However, these analyses, neither alone nor in combination, provide a definitive answer regarding allergenic potential, and for this reason there has been interest in exploring a more holistic approach (and more definitive assessment) that may be provided by suitable animal models. 

Repeats in proteins can also be used to limit domain definitions. If a protein contains two homologous repeats, with a common motif separated by 200 amino acids, it can be inferred that the domain cannot be larger than 200 residues, although in this case the domain boundaries may not be known. 

A number of toxicologically active 2,3,7,8-substituted PCDDs and PCDFs, planar PCBs and PCDD, PCDF, and PCDT homologs were measured in fish, SPMDs, and sediments. Only two target compounds exceeded the detection limits of 0.2-1 pg g in SPMD field blanks (see definition in Chapter 5). These exceptions were octachlorodibenzo-p-dioxin (OCDD) and octachlorodibenzofuran (OCDF) which were present in SPMDs at about 5 pg g However, negative... 

Several epoxy powders were formulated in a homologous series where the EEW of the base resin changed from 858 8/eq. to 1487 8/eq. All formulations contained 10% carboxyl-terminated rubber, were extruded two times, and were cured with calculated amounts of P-108. The standard cure schedule of 200OC for 15 minutes was used. MEK absorptions were measured in the usual manner. A definite dependence of MEK absorption on EEW was found. Table V summarizes the data. 

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