Levels of Activating Enzymes

Levels of conjugating enzymes, such as glutathione transferases, are also known to be influenced by gender and species differences as well as by drugs and other environmental factors. All of these factors will in turn affect the detoxication process. 

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Modulation of the levels of active enzyme by tnm-cinnamic acid. Planta 169, 97-107. 

In most applications the level of enzyme used is very low and is inactivated during the processing, allowing the enzyme to be regarded as a processing aid. There are many potential food applications for enzymes which require activity levels or processing conditions which would either make the economics unfavorable or would leave undesirable levels of active enzyme in the final... 

The Str gene cloned from R. serpentina has been expressed in various organisms, among others E. coli (288) and insect cells (289). In both cases, this resulted in high levels of active enzyme. Two forms were found, a high-and low-molecular-mass form both had activity, the values being similar... 

The design of a proper drying process should guarantee a high level of active enzyme. Generally, enzyme activity after drying is a function of the composition of the initial liquid to be dehydrated, the process parameters, and the physicochemical... 

It was therefore proposed that either the viral polymerase is extremely instable and continuous protein synthesis is needed to restore the level of active enzymes (IO), or that proteolytic inactivation of the viral replicase leads to the decline of the rate of RNA synthesis observed late in the infectious cycle (81). 

D-Aminoacid oxidase has been isolated from a nnmber of yeasts, and the nucleotide sequence of the enzyme from Rhodotorula gracilis ATCC 26217 has been established (Alonso et al. 1998). The gene could be overexpressed in Escherichia coli, and levels of the enzyme were greater under conditions of low aeration the enzyme isolated from the recombinant organisms was apparently the apoenzyme since maximum activity required the presence of FAD. 

In addition to a-l-PI, there are other examples of the presence of Met(O) residues in proteins isolated from biological material. Proteins found in lens tissue are particularly susceptible to photooxidation and because of the long half-lives of these proteins, any oxidation could be especially detrimental. In this tissue, protein synthesis is localized to the outer region of the tissue and most proteins are stable for the life of the tissue - ". It is thus somewhat surprising that not only is there no Met(O) residues in the young normal human lens but even in the old normal human lens only a small amount of Met(O) residues is found . However, in the cataractous lens as much as 65% of the Met residues of the lens proteins are found in the form of Met(0) . Whether this increase in Met(O) content in these proteins is a cause or a result of the cataracts is not known. In order to determine whether the high content of Met(O) in the cataractous lens is related to a decreased activity of Met(0)-peptide reductase, the level of this enzyme was determined in normal and cataractous lenses. It can be seen from Table 9 that there are no significant differences between the levels of Met(0)-peptide reductase in normal and cataractous lenses. In spite of these results, however, it is still possible that the Met(0)-peptide... 

Hepatic reperfusion injury is not a phenomenon connected solely to liver transplantation but also to situations of prolonged hypoperfusion of the host s own liver. Examples of this occurrence are hypovolemic shock and acute cardiovascular injur) (heart attack). As a result of such cessation and then reintroduction of blood flow, the liver is damaged such that centrilobular necrosis occurs and elevated levels of liver enzymes in the serum can be detected. Particularly because of the involvement of other organs, the interpretation of the role of free radicals in ischaemic hepatitis from this clinical data is very difficult. The involvement of free radicals in the overall phenomenon of hypovolemic shock has been discussed recently by Redl et al. (1993). More specifically. Poll (1993) has reported preliminary data on markers of free-radical production during ischaemic hepatitis. These markers mostly concerned indices of lipid peroxidation in the serum and also in the erythrocytes of affected subjects, and a correlation was seen with the extent of liver injury. The mechanisms of free-radical damage in this model will be difficult to determine in the clinical setting, but the similarity to the situation with transplanted liver surest that the above discussion of the role of XO activation, Kupffer cell activation and induction of an acute inflammatory response would be also relevant here. It will be important to establish whether oxidative stress is important in the pathogenesis of ischaemic hepatitis and in the problems of liver transplantation discussed above, since it would surest that antioxidant therapy could be of real benefit. 

Therefore, it is currently believed that anandamide is formed from membrane phospholipids (Fig. 4) through a pathway that involves (1) a trans-acylation of the amino group of phosphatidylethanolamine with arachidonate from the sn-1 position of phosphatidylcholine and (2) a D-type phosphodiesterase activity on the resulting A-arachidonylphosphati-dylethanolamide (NAPE). Synthesis of anandamide is presumably regulated at the levels of both enzymes, the A-acyltranferase and the phospholipase D, by stimuli that raise intracellular calcium or by receptors linked with cAMP and PKA. It has been shown that anandamide is formed when neurons are depolarized and, therefore, the intracellular calcium ion levels are elevated (Cadas, 1996). 

The decreased denaturating action of the precursor and procedure enables one to immobilize reduced amounts of biomaterial. It was demonstrated in Ref. [55] that biocatalysts prepared by entrapping endo-l,3-P-D-glucanase and a-D-galactosidasc in amounts comparable to that in living cells had a reasonable level of activity. When the TEOS is applied, the enzyme content in silica matrix can be up to 20-30 wt.% to counterbalance losses due to denaturation [50]. 

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