Prebiotic origin of glycolytic metabolism: histidine and cysteine can produce acetyl CoA
from glucose via reactions homologous to non-phosphorylated Entner-Doudoroff pathway.
These modifications are brought about by different enzymes that recruit different substrates like kinases use ATP for phosporylation; acetylases use acetyl CoA for acetylation, etc.
Acetylation of proteins by histone acetyl transferases uses acetyl CoA as acetyl group donor molecule and is the most widely studied acetylation system, while little knowledge is available on acetyl CoA independent acetylation of proteins, although asprin mediated acetylation of cyclo-oxygenase is known for a long time (71).
Acetylation of proteins by HAT/HDAC system using acetyl CoA is among the most widely studied posttranslational modification and plays an important role in determining cellular responses to variety of damage causing agents.
Establishment of the enzymatic protein acetylation independent of acetyl CoA: recombinant glutathione S- transferase 3-3 is acetylated by a novel membrane-bound transacetylase using 7, 8-diacetoxy-4-methyl coumarin as the acetyl donor.FEBS Lett 2002; 530: 139-42.
The enzyme follows ping-pong kinetics, with the occurrence of a covalent acetyl-enzyme intermediate at the active site cysteine using acetyl CoA or another acetyl donor, and then transfers the acetyl group to the substrate's exocyclic nitrogen (N-acetylation) or the hydroxyl oxygen (O-acetylation) .
We made attempts to examine whether acetyl CoA, a physiological acetyl group donor for protein acetylation, is a substrate for CRTAase.
Acetyl CoA was also found to bind to the same active site.
CRTAase was reported to utilize acetyl CoA as the acetyl group donor .
The accumulated pyruvate enters the GABA shunt pathway and is converted to citrate which is acted upon by citrate lyase and converted to acetyl CoA
, used for cholesterol synthesis .
The metal actinide surfaces would by surface metabolism generate acetate which could get converted to acetyl CoA
and then to cholesterol which functions as the primal prebiotic molecule self organizing into self replicating supramolecular systems, the lipid organism [8,9,35].