Racemization hypothesis of neurodegeneration (RHND)

Parkinson's Disease and Neurodegeneration: GABA-Collapse Hypothesis

Neurodegenerative diseases constitute a heterogeneous group of age-related disorders that are characterized by a slow but irreversible deterioration of brain functions. Evidence accumulated over more than two decades has implicated calcium-related homeostatic mechanisms, giving rise to the Ca(2+) hypothesis of brain aging and, ultimately, cell death. Gamma-aminobutyric acid (GABA) is the main i...

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...