Preferential degradation

It is possible to prepare pyrimidines from other heteromonocyclic compounds by a variety of processes, or from fused heterobicyclic systems which already contain a pyrimidine ring by preferentially degrading the unwanted second ring. In the latter case, the bicyclic system may best be made from a pyrimidine in the first place, occasionally even from the self-same pyrimidine to which it reverts on degradation. Such syntheses may be of interest but are certainly not of any utility. 

Kerr181 has suggested that treatment of maize starch granules with 0.1 to 0.15 N sulfuric acid results in preferential degradation of the amylopectin,... 

A methanotrophic biofilter is a biofilter in which methanotrophs are present. In a biofilter, a gas- or aqueous-phase contaminant stream is passed through a media on which the bacteria are growing. The media can be of several different materials, including compost, peat, soil material, or granular activated carbon. Specific strains of bacteria may be introduced into the filter and optimal conditions provided to preferentially degrade specific compounds. 

Different isomers may have different rates of degradation in the environment which would change the overall risk. For example, in the case of cypermethrin, the trans-isomers were preferentially degraded over the cis-isomers. Of the two active isomers of this insecticide, the (lR)-ds-(aS)-isomer was degraded more slowly than (1 R)-tmns-(u. S)-i sorn er by bacteria and in whole sediments [150]. By selecting for the isomer (or process that produces a majority of that isomer) with the more rapid degradation profile, the ecological risk should be reduced. 

An ATP-dependent DNase has been partially purified from extracts of E. coli by Oishi (86) and Barbour and Clark (37). It shows an absolute requirement for magnesium or manganese ion and has a broad pH optimum ranging from pH 7.5 to 9.5. The partially purified enzyme preferentially degrades native DNA (including glucosylated T4 DNA) and has an almost absolute requirement for ATP or dATP. Current preparations of the enzyme are also active on denatured DNA however, there is only a slight stimulation of hydrolysis by added ATP. This latter activity may therefore represent some contamination with exonuclease I. The mode of attack is stated to be exonucleolytic. 

JD Weete. Preferential degradation of noncholine phosphatides in soybean lecithin by thermalization. J Am Oil Chem Soc 71 1195-1199, 1994. 

During hormonal stimulation of Ptdlns 4,5-P2 hydrolysis there appears to be a preferential degradation of molecules, such as diacylglycerol and phosphatidic acid, which contain arachidonate in the 2-position. Two separate pathways have been proposed for the release of arachidonic acid from these two products of the phosphoinositide response. The first proposes that diacylglycerol is the source of the liberated arachidonate and that diacylglycerol lipase acts on the DG released by hydrolysis of phosphoinositides. The second suggests that a phosphatidic acid-specific phospholipase A2 is responsible for cleaving the arachidonic acid from phosphati-date. 

Salo, D. C., Lin, S. W., Pacifici, R. E., and Davies, K. J., Superoxide dismutase is preferentially degraded by a proteolytic system from red blood cells following oxidative modification by hydrogen peroxide. Free Radicals Biol. Med. 5, 335—339 (1988). 

Van Mooy, B. A. S., Keil, R. G., and Devol, A. H. (2002). Impact of suboxia on sinking particulate organic carbon Enhanced carbon flux and preferential degradation of amino acids via denitrification. Geochim. Cosmochim. Acta. 66, 457 65. 

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