Enzymatic factors

L4. Lerman, S., Enzymatic factors in experimental galactose cataract. Science 130, 1473-1474 (1959). 

In comprehensive studies, the hydrolysis of some 30 naphthyl esters by human, rat, and mouse liver carboxylesterases was investigated [43], A general trend that was apparent was that the rate of hydrolysis of a- and /3-naphthyl carbonates (7.21, R = alkyl or arylalkyl) catalyzed by human microsomes or rat hydrolases showed a tendency to decrease with increasing lipophilic-ity (range ca. 2 to 5). A similar trend was not seen with naphthyl aryl carbonates nor with a-naphthyl carboxylates. These results tell us that, even with purified enzymes and large series of substrates, it is very difficult indeed to discern sound structure-hydrolysis relationships due to the complexity of the structural and enzymatic factors involved. 

Volatile aldehydes, and (E)-2-nonenal in particular, had already been identified as the cause of "rancid odors" in beer (7,8). These substances result firom the oxidation of unsaturated fatty acids. The direct precursor of (E)-2-nonenal and others carbonyl components is linoleic acid (Ci8 2 A 9,12) (9). Volatile aldehydes may be derived firom fatty acids in various manners. Chemical auto-oxidative factors would seem to provide the most likely explanation for the presence of these components in oak stave wood after seasoning in the open air. On the other hand, enzymatic factors may explain the presence of ese components while the tree is still standing or immediately after it has been cut. Additional research is necessary to pinpoint the exact formation and accumulation mechanisms of these molecules in the wood. 

The stability of a drug in the gut is influenced by both chemical and enzymatic factors. Protection from chemical degradation may be accomplished via coating... 

ST26 Verstraete. A.G. and Wieme, R.J. (1986). An enzymatic factor may interfere with the digoxin on the Stratus analyzer. Ther. Drug. Monit. 8, 244. 

Pahlman R, Pelkonen 0. 1987. Mutagenicity studies of different polycyclic aromatic hydrocarbons The significance of enzymatic factors and molecular structure. Carcinogenesis 8 773-778. 

Physico-chemical and enzymatic factors affecting fruit stability... 

Reese Does Cowling now withdraw his original suggestion that the enzymes of wood-destroying fungi act at a distance Does he believe that non-enzymatic factors may be involved ... 

Although direct and indirect mechanisms are still regarded as useful models and some researchers use the direct and indirect terminologies to explain the experimental results of bioleaching, based on very fundamental shortcomings such as the nonexistence of enzymatic factors, some authors have been quoted to have combined the two mechanisms into one single process. 

For many years the biosynthesis of melanin was thought to result from the spontaneous oxidation and polymerization of dopachrome produced by the tyrosinase-catalyzed hydroxylation of tyrosine to dopa and subsequent oxidation (5 ). In addition to tyrosinase, however, several enzymatic factors have been recently identified in mammalian tissues that appear to regulate melanogenesis at intermediate steps distal to those involving tyrosine and dopa. The factors include dopachrome conversion factor, dihydroxyindole blocking factor, dihydroxyindole conversion factor and dopachrome oxidoreductase (54-59). 

Species, sex, age, genetics, e.g., variability in enzymatic factors such as polymorphisms (cytochrome systems) or tissue repair mechanisms ... 

Arakane, Y., H. Hoshika, and N. Kawashima et al. 2000. Comparison of chitinase isozymes from Yam tuber-enzymatic factor controlling the lytic activity of chitinases. Biosci. Biotechnol. Biochem. 64 723-730. 

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