Chemical Racemization of MethylL-β-Acetylthioisobutyrate

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...

Racemization of lysine by a pseudomonad.

The recent paper by Huang and Davisson (J. Bacteriol., 76, 495, 1958) on the distribution of lysine racemase in bacteria reports its occurrence in only a few species of Escherichia and Proteus. Various other bacteria including 22 strains of various genera of the Pseudomonadaceae did not possess such activity. I wish to report evidence for the occurrence of lysine racemase activity in a Pseudomo...

Racemization of amino acids in marine sediments.

Isoleucine, one of several amino acids isolated from a suite of welldated deep-sea cores, shows a progressive increase in the degree of racemization with the age of the sediment. Amino acids in sediments show an initial rate of racemization almost an order of magnitude faster than the rate observed for free amino acids at a comparable pH and temperature. The observed kinetics depend on a variet...