STUDIES ON RACEMIZATION

Amino Acid Racemization

Racemization and epimerization.

In recent reports (I ) the term racemization is used inappropriately. It is stated in both reports that Lisoleucine racemizes to D-alloisoleucine. This reaction is epimerization, not racemization. Racemization of L-iSOleucine results in the formation of DLisoleucine. As stated in Eliel (2): "'racemization is the process of producing a racemic modification starting with one of the pure enantiome...

Racemization of Meteoritic Amino Acids

Meteorites may have contributed amino acids to the prebiotic Earth, affecting the global ratio of right-handed to left-handed (D/ L) molecules. We calculate D/ L ratios for seven biological, α-hydrogen, protein amino acids over a variety of plausible parent body thermal histories, based on meteorite evidence and asteroid modeling. We show that amino acids in meteorites do not necessarily underg...

Chiroptical properties and the racemization of pyrene and tetrathiafulvalene-substituted allene: substitution and solvent effects on racemization in tetrathiafulvalenylallene.

Dissymmetric 1,3-diphenylallene derivative 3 connected with 4,5-bis(methyl-thio)tetrathiafulvalenyl and 1-pyrenyl substituents was prepared and characterized. The molecular structure was determined by X-ray crystallographic analysis. Optical resolution was accomplished using a recycling chiral HPLC, and its chiroptical properties were examined with optical rotation and electronic circular dichr...

22. Data Report: Amino Acid Racemization Geochronological Studies of Selected Leg 155 Samples

Amino acid racemization measurements have been conducted on selected samples from Ocean Drilling Program (ODP) Leg 155 to evaluate the utility of this method for geochronological purposes. Sample size limited the number of analyses, but samples that were successfully processed included one sample of Holocene age, one from oxygen isotope Substage 5e, and two pre-Substage 5e samples. These latter...