Abstract
The enzyme orotate phosphoribosyl transferase (OPRTase) is involved in the de novo pyrimidine nucleotide biosynthesis; it is a good target for antimicrobial agents. Also, some of the cancerous cells are known to depend on de novo pathway, this enzyme could be a potential drug target for cancer therapy. Orotate phosphoribosyl transferase is an important enzyme, which converts orotate to orotate monophosphate in the fifth step of pyrimidine biosynthesis. As the enzyme is from a hyperthermophile it is known to be stable at high temperatures and can be used as a model organism. Based on the importance of the enzyme, OPRTase from the extreme thermophile, Thermus thermophilus HB8 has been cloned, purified by ion exchange and size exclusion chromatography (SEC). Very tiny crystals appeared in the condition 0.2 M calcium acetate hydrate, 0.1 M sodium cacodylate trihydrate pH 6.5 and 18% w/v polyethylene glycol 8,000.
