🔬biological chemistry i review

key term - Phosphoribosyltransferase

Definition

Phosphoribosyltransferase refers to a group of enzymes that catalyze the transfer of a phosphoribosyl group from phosphoribosyl pyrophosphate (PRPP) to various acceptor molecules, playing a crucial role in nucleotide metabolism and salvage pathways. These enzymes are essential for recycling nucleotides, allowing cells to efficiently synthesize nucleotides from pre-existing bases and ribose-5-phosphate, rather than relying solely on de novo synthesis. This process helps maintain the nucleotide pool necessary for DNA and RNA synthesis.

5 Must Know Facts For Your Next Test

  1. Phosphoribosyltransferase enzymes are classified based on the specific substrates they act upon, including purines and pyrimidines.
  2. These enzymes help prevent the loss of nucleotide bases through degradation, enabling cells to efficiently utilize available resources.
  3. In humans, defects in phosphoribosyltransferase can lead to disorders such as Lesch-Nyhan syndrome, which is characterized by neurological and behavioral abnormalities due to impaired purine metabolism.
  4. The regulation of phosphoribosyltransferase activity is critical for maintaining a balance between de novo synthesis and salvage pathways, impacting overall nucleotide availability.
  5. Research into phosphoribosyltransferase has implications for cancer therapy, as targeting nucleotide metabolism can disrupt the proliferation of cancer cells.

Review Questions

  • How does phosphoribosyltransferase facilitate nucleotide recycling in cellular metabolism?
    • Phosphoribosyltransferase facilitates nucleotide recycling by catalyzing the transfer of phosphoribosyl groups from PRPP to free bases, converting them into nucleotides. This process is part of the salvage pathways that allow cells to efficiently recover and reuse components from degraded nucleotides instead of synthesizing new ones from scratch. By doing so, phosphoribosyltransferase helps maintain an adequate supply of nucleotides necessary for vital cellular functions such as DNA replication and RNA transcription.
  • Discuss the potential consequences of impaired phosphoribosyltransferase activity in humans.
    • Impaired phosphoribosyltransferase activity can lead to significant metabolic disorders, such as Lesch-Nyhan syndrome, which arises from a deficiency in HGPRT. This deficiency results in the accumulation of uric acid due to ineffective purine metabolism, leading to neurological symptoms and behavioral issues. Furthermore, a lack of effective nucleotide recycling can disrupt the balance of nucleotide pools, potentially impacting cellular growth and division. Such impairments can also contribute to increased susceptibility to certain diseases or conditions related to nucleotide deficiencies.
  • Evaluate how understanding phosphoribosyltransferase could influence therapeutic strategies in cancer treatment.
    • Understanding phosphoribosyltransferase is crucial for developing therapeutic strategies in cancer treatment since these enzymes play a vital role in regulating nucleotide metabolism. Cancer cells often exhibit increased rates of proliferation, leading to higher demands for nucleotides. Targeting phosphoribosyltransferase could disrupt the nucleotide salvage pathways, effectively limiting the availability of nucleotides necessary for rapid cell division. By inhibiting these enzymes, researchers may develop treatments that selectively impair cancer cell growth while sparing normal cells, contributing to more effective and less toxic cancer therapies.

"Phosphoribosyltransferase" also found in: