The crystal structure of trichosanthin (TCS) in space group C2 hasbeen refined by PROLSQ and XPLOR to an R-factor of 0. 204 for 33, 531 reflectionswith F。≥2-σ(F。) between 6 to 1. 9 A resolution. The root mean squa...The crystal structure of trichosanthin (TCS) in space group C2 hasbeen refined by PROLSQ and XPLOR to an R-factor of 0. 204 for 33, 531 reflectionswith F。≥2-σ(F。) between 6 to 1. 9 A resolution. The root mean square(r. m. s. ) devi-ations of bond lengths and bond angles from the standard values are 0. 015 A and 2.77°, respectively. The overall fold of the molecule of TCS is, in general, similar to oth-er RIPs, but there are some differences in secondary structure and in the active sitecleft. An overlay of the two molecules (shown by Mol. A and Mol. B), which are notrelated by symmetry in an asymmetric unit, results in an r. m. s. deviation of 0. 850Afor the main chain atoms. The backbones of the C-terminus of the two molecules arequite different. The structures of the water in two molecules are not completely analo-gous. In the active site cleft of Mol. B, the bonding sites of three water molecules toprotein are similar to those of N atoms of formycin ring in the structure of pokeweedantiviral protein complexed with formycin 5-monophosphate, and the side chains of twoTyr70 in the two crystalline forms of TCS show a similar orientation, which is differentfrom that of the corresponding residue in ricin A-chain.展开更多
Crotin Ⅱ is one of the ribosome inactivating proteins (RIPs). It belongs to RNA hydrolase. The crystals of crotin Ⅱ are hexagonal with a=b= 94. 62, c=28. 44 A, space group P61, Mr= 14900 Da. The structure was solved...Crotin Ⅱ is one of the ribosome inactivating proteins (RIPs). It belongs to RNA hydrolase. The crystals of crotin Ⅱ are hexagonal with a=b= 94. 62, c=28. 44 A, space group P61, Mr= 14900 Da. The structure was solved by molecularreplacement methed using the molecular structure of RNase T1 as a search model andrefined to R= 0. 25 for the reflections within 10- 2. 5 A resolution range. The refinedmodel cotains one α-helix, one two-strand antiparallel β-sheet and one five-strand an-tiparallel β-sheet. Four conservative residues His47, Glu77, Arg102 and His117 gathering in the cleft of the structure form the possible active site of crotin Ⅱ.展开更多
文摘The crystal structure of trichosanthin (TCS) in space group C2 hasbeen refined by PROLSQ and XPLOR to an R-factor of 0. 204 for 33, 531 reflectionswith F。≥2-σ(F。) between 6 to 1. 9 A resolution. The root mean square(r. m. s. ) devi-ations of bond lengths and bond angles from the standard values are 0. 015 A and 2.77°, respectively. The overall fold of the molecule of TCS is, in general, similar to oth-er RIPs, but there are some differences in secondary structure and in the active sitecleft. An overlay of the two molecules (shown by Mol. A and Mol. B), which are notrelated by symmetry in an asymmetric unit, results in an r. m. s. deviation of 0. 850Afor the main chain atoms. The backbones of the C-terminus of the two molecules arequite different. The structures of the water in two molecules are not completely analo-gous. In the active site cleft of Mol. B, the bonding sites of three water molecules toprotein are similar to those of N atoms of formycin ring in the structure of pokeweedantiviral protein complexed with formycin 5-monophosphate, and the side chains of twoTyr70 in the two crystalline forms of TCS show a similar orientation, which is differentfrom that of the corresponding residue in ricin A-chain.
文摘Crotin Ⅱ is one of the ribosome inactivating proteins (RIPs). It belongs to RNA hydrolase. The crystals of crotin Ⅱ are hexagonal with a=b= 94. 62, c=28. 44 A, space group P61, Mr= 14900 Da. The structure was solved by molecularreplacement methed using the molecular structure of RNase T1 as a search model andrefined to R= 0. 25 for the reflections within 10- 2. 5 A resolution range. The refinedmodel cotains one α-helix, one two-strand antiparallel β-sheet and one five-strand an-tiparallel β-sheet. Four conservative residues His47, Glu77, Arg102 and His117 gathering in the cleft of the structure form the possible active site of crotin Ⅱ.
