purine

(noun)

any of a class of organic heterocyclic base containing fused pyrimidine and imidazole rings; they are components of nucleic acids

Related Terms

Examples of purine in the following topics:

  • Purine and Pyrimidine Synthesis

    • Unlike pyrimidines, purines are biologically synthesized as nucleotides and in particular as ribotides.
    • The carbon and nitrogen atoms of the purine ring, 5 and 4 respectively, come from multiple sources.
    • CTP synthase is activated by GTP, a purine.
    • This acts to balance the relative amounts of purine and pyrimidine nucleotides.
    • Adenine and guanine are purines and cytosine and thymine are pyrimidines.

  • Inhibiting Essential Metabolite Synthesis

    • Because tetrahydrofolate is essential for purine and pyrimidine synthesis, its deficiency can lead to inhibited production of DNA, RNA and proteins.
    • The purine analogues are the third type of antimetabolite antibiotics and they mimic the structure of metabolic purines .
    • Two of the four bases in nucleic acids, adenine and guanine, are purines.
    • Purine analogues disrupt nucleic acid production.
    • Distinguish between the three main types of antimetabolite antibiotics (antifolates, pyrimidine and purine analogues)

  • Some Polycyclic Heterocycles

    • Derivatives of the simple fused ring heterocycle purine constitute an especially important and abundant family of natural products.
    • Xanthine and uric acid are products of the metabolic oxidation of purines.
    • Examples of common methylated purines are shown above in the second diagram.

  • DNA Repair

    • Transition substitution refers to a purine or pyrimidine being replaced by a base of the same kind; for example, a purine such as adenine may be replaced by the purine guanine.
    • Transversion substitution refers to a purine being replaced by a pyrimidine or vice versa; for example, cytosine, a pyrimidine, is replaced by adenine, a purine.

  • DNA and RNA

    • Adenine and guanine are classified as purines.
    • The primary structure of a purine consists of two carbon-nitrogen rings.
    • Bases can be divided into two categories: purines and pyrimidines.
    • Purines have a double ring structure, and pyrimidines have a single ring.

  • The Structure and Sequence of DNA

    • The nitrogenous base can be a purine such as adenine (A) and guanine (G), characterized by double-ring structures, or a pyrimidine such as cytosine (C) and thymine (T), characterized by single-ring structures.
    • Only the pairing between a purine and pyrimidine can explain the uniform diameter.
    • That is to say, at each point along the DNA molecule, the two sugar phosphate backbones are always separated by three rings, two from a purine and one from a pyrimidine.
    • Base pairing takes place between a purine and pyrimidine stabilized by hydrogen bonds: A pairs with T via two hydrogen bonds and G pairs with C via three hydrogen bonds.

  • Nitrogenous Waste in Birds and Reptiles: Uric Acid

    • Uric acid is a compound similar to purines found in nucleic acids.
    • The enzyme xanthine oxidase makes uric acid from xanthine and hypoxanthine, which in turn are produced from other purines.

  • The DNA Double Helix

    • For example, a certain purine can only pair with a certain pyrimidine.

  • Biosynthesis and Energy

    • Biosynthetic building blocks utilized by organisms include amino acids, purines, pyrimidines, lipids, sugars, and enzyme cofactors.

  • Types of RNA

    • Bases can be divided into two categories: purines and pyrimidines.
    • Purines have a double ring structure, and pyrimidines have a single ring.