Partial purification and properties of guanosine triphosphate cyclohydrolase fromDrosophila melanogaster

✍ Scribed by Ching Liang Fan; Gene M. Brown

• Book ID: 104784245
• Publisher: Springer
• Year: 1976
• Tongue: English
• Weight: 574 KB
• Volume: 14
• Category: Article
• ISSN: 0006-2928
• DOI: 10.1007/bf00484765

✦ Synopsis

The first enzyme (named GTP cyclohydrolase) in the pathwayfor the biosynthesis of pteridines has been partially purified from extracts of late pupae and young adults of Drosophila melanogaster. This enzyme catalyzes the hydrolytic removal from GTP of carbon 8 as formate and the synthesis of 2-amino-4hydroxy-6-(D-erythro-l',2',Y-trihydroxypropyl)-7,8-dihydropteridine triphosphate (dihydroneopterin triphosphate). Some of the properties of the enzyme are as follows." it functions optimally at pH 7.8 and at 42 C; activity is unaffected by KCl and NaCl, but divalent cations ( Mg z +, Mn z+ , Zn 2+ , and Ca e + ) are inhibitory; the Kin for GTP is 22 #M; and the molecular weight is estimated at 345,000 from gel filtration experiments. Of a number of nucleotides tested, only GDP and dGTP were used to any extent as substrate in place of GTP, and these respective compounds were used only 1.8%o and 1.5% as well as GTP.