epimerization


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Related to epimerization: racemization, Mutarotation

epimerization

[‚e·pim·ə·rə′zā·shən]
(organic chemistry)
In an optically active compound that contains two or more asymmetric centers, a process in which only one of these centers is altered by some reaction to form an epimer.
References in periodicals archive ?
C-3 epimerization of vitamin D3 metabolites and further metabolism of c-3 epimers: 25-hydroxyvitamin D3 is metabolized to 3-epi-25-hydroxyvitamin D3 and subsequently metabolized through c-1 or c-24 hydroxylation.
[9], in this processing step loss of (-)-epicatechin and (+)-catechin is partly attributed to heat-induced epimerization to (-)-catechin.
No epimerization could be detected for the two compounds investigated (Figure 1).
The reason might be that the main reason for loss of deltamethrin is evaporation, but the washing process or the drying in the sun after washing causes the epimerization. UV light is known to cause deltamethrin epimerization.
Some of the reported catalysts suffer from disadvantages such as high acidity, the non-catalytic nature of the reagents, high temperatures, long reaction times or side isomer- ization, epimerization and rearrangement reactions [12-14].
The loss of moisture of sweet potato during storage may have influenced the occurrence of polymerization and epimerization of cell wall microfibrils leading to the thickening of the cell walls and subsequent release of carotenoids during in vitro digestion.
Otoliths as recorders of palaeoenvironments: comparison of radiocarbon age and isoleucine epimerization in Pleistocene golden perch Macquaria ambigua otoliths from Willandra Lakes.
These solutions were stored at -20[degrees]C for several days without apparent loss of detectable alkaloids, other than the expected epimerization. Working standard solutions (50-500 ng [mL.sup.-1]) in methanol/ water (2:1) were prepared daily.
Epirubicin differs from adriamycin by the epimerization of the OH group in position 4' of the aminosugar moiety and has been shown to be less toxic during chemotherapeutic treatments against metastatic breast cancers (Ganzina 1983; reviewed by Hortabagyi 2000).
The epimerization strongly decreases the compound's biologic efficacy; the anabolic potency of TbOH-17[alpha] is only about 5% of that of TbOH-17[beta] (9), and the affinity to the recombinant human androgen receptor (rhAR) is reduced to about 4% (10).
Feringa has made efficient use of 5-menthyl-oxy-2(5H)-furanones to provide enantiomerically pure synthons through "crystallization induced epimerization".
The existence of D-isomers may be explained by racemization [22] of L-aspartic acid or epimerization of L-aspartyl residues in the polypeptides.