Used_in The definition of C++ [ c++.syntax.html ]. Used_in The definition of Java [ java.syntax.html ] Notation This uses my XBNF Extended BNF Notation where | indicates or, (...) indicates priority. For more information see [ intro_ebnf.html ].
To look at it in another way: Thymine(uracil in RNA) and cytosine are pyrimidines. Pyrimidines are single-ringed organic base that will only attach to purines, or adenine and guanine by hydrogen bond. Because cytosine and thymine are both pyrimidines, it cannot form a hydrogen bond with each other.
Xanthine compounds such as theophylline have diuretic properties. xanthine calculi. see xanthine urolith. dimethyl xanthine. theobromine.xanthine oxidase. key enzyme in the pathway for purine breakdown. Catalyzes the conversion of hypoxanthine to xanthine and then to uric acid.anthine compounds such as theophylline have diuretic properties. xanthine calculi. see xanthine urolith. dimethyl xanthine. theobromine.