The enzymes which catalyze the reversible phosphorolysis of pyrimidine nucleosides are involved in the degradation of these compounds and in their utilization as carbon and energy sources, or in the rescue of pyrimidine bases for nucleotide synthesis. phosphate + thymidine = 2-deoxy-alpha-D-ribose 1-phosphate + thymine Homodimer. Belongs to the thymidine/pyrimidine-nucleoside phosphorylase family.