De novo synthesis of purine nucleotides.�provide every information involved in the synthesis and the information must be more than 3 pages.

Answer 1

De novo synthesis of purine nucleotides is a complex biochemical process that occurs in all living organisms. Purine nucleotides are essential for a variety of cellular functions, including DNA and RNA synthesis, energy metabolism, and signal transduction. The de novo synthesis of purine nucleotides involves a series of enzymatic reactions that convert simple precursors into the final purine nucleotides adenine and guanine.

The pathway for de novo purine nucleotide synthesis is divided into two branches, one leading to the synthesis of inosine monophosphate (IMP), the precursor of adenine nucleotides, and the other leading to the synthesis of guanosine monophosphate (GMP), the precursor of guanine nucleotides. Both pathways share common metabolic intermediates and enzymes before branching off to produce the respective purine nucleotide bases.

The first step in de novo purine nucleotide synthesis is the formation of phosphoribosyl pyrophosphate (PRPP) from ribose-5-phosphate, an intermediate of the pentose phosphate pathway, and ATP. This reaction is catalyzed by the enzyme PRPP synthetase and is the committed step in purine nucleotide biosynthesis. PRPP serves as the precursor for the synthesis of both adenine and guanine nucleotides.

The synthesis of IMP, the precursor of adenine nucleotides, begins with the condensation of PRPP with glutamine to form 5-phosphoribosylamine, a reaction catalyzed by the enzyme amidophosphoribosyltransferase (also known as glutamine-PRPP amidotransferase). This step is regulated by feedback inhibition by adenine nucleotides and is a key regulatory point in purine nucleotide synthesis. Subsequent steps involve the conversion of 5-phosphoribosylamine to IMP through a series of enzymatic reactions, including the conversion of IMP to adenosine monophosphate (AMP) and ultimately adenosine triphosphate (ATP).

The synthesis of GMP, the precursor of guanine nucleotides, also begins with the condensation of PRPP with glutamine to form 5-phosphoribosylamine. This is followed by a series of enzymatic reactions that convert 5-phosphoribosylamine to GMP through the synthesis of inosine monophosphate (IMP) as an intermediate. The final steps in GMP synthesis involve the conversion of IMP to xanthosine monophosphate (XMP) and ultimately GMP.

The de novo synthesis of purine nucleotides is tightly regulated to meet the demands of the cell for nucleotide precursors while preventing the accumulation of excess purine nucleotides, which can be toxic. Regulation of purine nucleotide synthesis occurs at multiple levels, including feedback inhibition by the end products of the pathway (adenine and guanine nucleotides), allosteric regulation of key enzymes, and transcriptional and post-translational mechanisms.

In summary, de novo synthesis of purine nucleotides is a complex biochemical process that involves the conversion of simple precursors into the final purine nucleotide bases adenine and guanine. The pathway is divided into two branches, one leading to the synthesis of adenine nucleotides and the other leading to the synthesis of guanine nucleotides. The synthesis of both IMP and GMP shares common intermediates and enzymes, with each branch ultimately producing the respective purine nucleotide base. Regulation of purine nucleotide synthesis is critical to maintaining nucleotide homeostasis in the cell and preventing the accumulation of toxic intermediates.