Transferase assays

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. 

Several bacterial and mammalian short-term tests for genetic toxicity as well as their biochemical and genetic rationale are described in Chapter 21 on toxicity testing. They include the salmonella assay, the Chinese hamster ovary cell/hypoxanthine-guanine phosphoribosyl transferase assay, the mouse lymphoma assay, the mammalian transformation assay, sister chromatid exchange, and the chromosome aberration assay. 

E519 Franzini, C., Cattozzo, G. and Morelli, A. (1989). Gamma-glutamyl transferase assay Results from two closed analytical systems equalized by mathematical manipulation. Biochim. Clin. 13, Suppl. 1/8, 310, Abstr. B 160. 

This reaction requires catalytic amounts of nucleotide. Activity in the transferase assay generally gives rates several times higher than those obtained in the synthetase assays [Eqs. (1) and (2)] and for this reason is often used for measurement of glutamine synthetase, especially in relatively crude preparations. However caution should be exercised in the use of the transferase assay as a similar reactitm can also be catalyzed by some glutaminases and certain other amidases (Meister et al., 1955), although in these cases the reaction is not dependent on ADP, phosphate, or divalent metal cation. Levintow et al. (1955) demonstrated that the synthetase activity and the ADP phosphate divalent cation dependent transferase activity are functions of the same enzyme. 

Fig. 1. Variation of oviduct and gonado-somatic indexes and poly(ADP-ribose)transferase activity in the oviduct during the reproductive cycle of the lizard Podarcis s.siculaRaf. The poly(ADP-ribose) transferase assay was performed as described in Ciarcia et al. (7). ( ) gonado/somatic index (O) oviduct/somatic index (A) poly(ADP-ribose) transferase activity in nuclear extracts. Arrow indicates when SNP appeared.

C18H33NO15 503.456 Partial struct, of naturally occurring asparagine linked oligosaccharides. Functions as a selective substrate in N-acetylglucosaminyl transferase assays. 

Ye S.-H. 1993. Hypoxanthine phosphoribosyl transferase assay of lead mutagenicity on keratino-cytes. Zhongguo Yaoli Xuebao 14, 145—147. Cited in Chapter 5, U.S. EPA, 2006. 

Table 1. Relative activity of fatty alcohols or 0)-hydroxyfatty acids in the feruloyl-CoA transferase assay...

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