While insulin-resistant tissues do suffer from a general paucity of DCIns due to the reduced
epimerization of myoIns, organs and tissues that retain their insulin sensitivity, like the ovary [79], display increased levels of DCIns and reduced levels of myoIns, due to the enhanced
epimerization of myoIns [80].
As seen with 25(OH)D,
epimerization can lead to high concentrations of the C-3 epimer, 3-epi1,25[(OH).sub.2][D.sub.2] in samples (22).
Lerner theorized that the fault was in the
epimerization process, the conversion of MI to DCI.
This disaccharide can be repeated several thousand times without any other chemical modification (i.e., sulfation, acetylation, and
epimerization) that are typical of the other GAGs [12].
HS structural diversity is based on a series of enzymatic reactions in the Golgi apparatus, which result in the removal of acetyl groups and sulfation, the
epimerization of glucuronic acid to iduronic acid, and the sulfation of the C-6 and C-3 hydroxyl groups of glucosamine and the C-2-hydroxyl groups of uronic residues [21].
The biosynthetic pathway consists of two major steps, methylation of myo-inositol which results in formation of an intermediate compound, ononitol, which undergoes
epimerization to form pinitol.
During fermentation, levels of both of these compounds were reduced, but (-)-catechin was formed due to heat-induced
epimerization.
White, "Kinetics of
epimerization of (+)-catechin and its rearrangement to catechinic acid," The Journal of Organic Chemistry, vol.
Since DBU actively catalyzes the formation of aspartimides, Asp piperidines, Asp
epimerization, and Asn dehydration [23, 31, 36], it was not added to the Fmoc removal reagent after Asp or Asn introduction to the growing peptide chains.
Strongly acidic or basic reaction conditions often lead to
epimerization or racemization in susceptible chiral compounds.
Linear regression analysis was used to estimate the impact of reported number washes on deltamethrin loss,
epimerization, and net height.
In that aspect, apparent recoveries significantly lower than 100% occurred for fumonisins (due to incomplete extraction), aflatoxins (due to matrix effects), ergot alkaloids (due to incomplete extraction and
epimerization in case of ergopeptides--note the difference between -ines and -inines), and some other polar analytes.