Methylmercuric hydroxide

Methylmercuric Nitrate. CH3HgN03 leaflets mp 100° v sol in w. Was prepd by Strecker (Ref 2) by treating methylmercuric hydroxide with nitric acid. It has to be handled with care, being a severe skin irritant... 

Methylmercuric Perchlorate. CH3HgC104 cry sts deflagrates ca 180°. Was prepd by treating methylmercuric hydroxide with 60% perchloric acid (Ref 3)... 

Suter KE. 1975. Studies on the dominant-lethal and fertility effects of the heavy metal compounds methylmercuric hydroxide, mercuric chloride and cadmium chloride in male and female mice. Mutat Res 30 365-374. 

Three different denaturants are currently employed formaldehyde glyoxal/dimethylsulfoxide (DMSO) or methylmercuric hydroxide (in order of decreasing popularity). It is also possible to elec-trophorese native RNA and denature RNA before transfer (3 gel volumes of 10% formaldehyde at 65°C for 30 min) (Khandjian and Meric, 1986). The sensitivity equals that obtained with denatured RNA. This approach can be useful for studying nicked RNA or to compare native with denatured RNA. Irrespective of the electrophoresis and transfer procedure to nylon, UV fixation was found to be beneficial. 

Methylmercuric hydroxide is very toxic and should not be used if it can be avoided. This denaturant reacts with the RNA, before electrophoretic fractionation, primarily with the imino groups of uridine and guanosine (Gruenwedel and Davidson, 1966 Bailey and Davidson, 1976) and electrophoresis is carried out in the presence of methylmercuric hydroxide. Sulfhydryl compounds (2-mercaptoethan-ol, DTT) can be used to displace methylmercuric hydroxide from imino groups. Methylmercuric hydroxide is not only extremely toxic but also volatile and should be handled in chemical hoods. All waste should be disposed of as toxic material (Junghans, 1983). 

Although RNA can bind as well as DNA to nitrocellulose, reproducible results are obtained only if RNA is carefully denatured. Among formaldehyde, glyoxal/DMSO, methylmercuric hydroxide, alkali and heat, the first two are most effective and give best binding, whereas alkali pretreatment can even be counterproductive (Thomas, 1983 Henderson et al., 1991). Recently, some attractive alternatives to these standard methods have become available (see below). The transfer of RNA from gel to membrane is as for DNA, of which the downward alkaline capillary transfer is the most attractive (Table 9.1 lA). 

Reactions with Hg2+ are virtually diffusion controlled56,57). Organomercury bonds, however, are kinetically inert. Reactions of, for example, H3C—Hg-OH (methylmercuric hydroxide) in aqueous media occur with replacement of hydroxide... 

The ability of various diaminopyrimidines to distinguish between analogous forms of the enzyme dihydrofolate reductase is the basis of some of the best contemporary anti-malarial and anti-bacterial therapy (see Section 4.0, p. 123, Tables 4.1 and 4.2, and Section 9.3.3 and 9.6). Let us first look at the differences that exist between various vertebrate types of the enzyme, none of which is much inhibited by trimethoprim (4.P), and then proceed to invertebrate types, which are highly susceptible to this drug. The enzyme from chicken liver has only 75% identity of amino acid sequence with that from ox liver. Moreover, methylmercuric hydroxide activates the avian type twelvefold whereas it inactivates the bovine type. The avian type is much richer in basic amino acids and has an isoelectric point of 8.4 compared to 6.8 for the bovine type. This result is achieved in the avian type by the presence of lysine at positions 32,106, and 154, whereas the bovine type has glycine, threonine, and glutamic acid, respectively, in these positions (Kumars/a/., 1980). 

Treatment of a solution of the [HFe(CO)4] ion with methylmercuric hydroxide gives the yellow-white compound (CH3Hg)2Fe(CO)4 191). This is unstable, disproportionating on standing or on heating to 80° C to form the insoluble, inert, stable polymeric derivative [HgFe(CO)4] (XXXV)... 

By incorporating methylmercuric hydroxide into agarose gel, a gel electrophoresis medium effectively containing a denaturing agent has been prepared and applied to the study of RNA s from avian myeloblastosis virus. ... 

Koerker, R. (1980) The cytotoxicity of methylmercuric hydroxide and colchicine in cultured mouse neuroblastoma cells. Toy. Appl Pharmacol 53, 458-469. 

Certain secondary structures in an RNA template may force the RTase to halt and/or terminate reverse transcription, which is often the cause of inefficient cDNA synthesis. To disrupt potential secondary structures, RNA templates are customarily denatured either by brief heating (30-60 sec at 100°C) or by treatment with methylmercuric hydroxide (CHjHgOH, 2.5 mM) followed by neutralization of the reagent with at least three times excess 2-MSH immediately prior to the addition of RTases (30). Despite the initial disruption of secondary structures hy either of the two methods mentioned earlier, RNA templates tend to regain, at least partially, their original secondary struaures during the period of incubation. The elevation of the reaction temperature, sometimes up to 55°C with AMV RTase, helps retard the process of refolding, while the elevated temperature increases the rate of polymerization by the RTase. However, the optimal temperature has to be compromised with the stability of the individual RTase. 

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