ABSTRACT
The polymorphism of glisentide has been investigated. Three polymorphs (I, II, III) have been prepared by recrystallization from different solvents and other polymorphic form (IV) was obtained by heating polymorph III at 100 degrees C. In addition, two 1:1 stoichiometric solvates containing carbon tetrachloride and dioxane have been crystallized and finally, an amorphous solid has been obtained. It has been observed that the polarity of the recrystallisation solvent and its ability to form hydrogen bonds have a great influence on the polymorphism of glisentide. The different solid forms of glisentide have been characterized using X-ray diffraction analysis, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), IR spectroscopy and optical microscopy. The recrystallization of polymorph I in melted form II and also the transition of form III-IV have been detected by DSC and X-ray diffraction analysis.
Subject(s)
Benzamides/chemistry , Cyclopentanes/chemistry , Hypoglycemic Agents/chemistry , Calorimetry, Differential Scanning , Carbon Tetrachloride , Crystallization , Dioxanes , Isomerism , Solvents , Spectrophotometry, Infrared , Thermogravimetry , X-Ray DiffractionABSTRACT
Modification of the only arginine residue present in proteins L7/L12 from Escherichia coli with phenylglyoxal, 2,3-butanedione and 1,2-cyclohexanedione is accompanied by functional alterations. The capacity of these proteins to promote polyphenylalanine synthesis and elongation factor G-dependent hydrolysis of GTP in L7/L12-depleted ribosomal cores is significantly decreased (more than 50%) on modification. Incubation of the butanedione- and cyclohexanedione-modified L7/L12 under regenerating conditions is accompanied by recovery of the original activity in polyphenylalanine synthesis. These results and the conservation of the arginine residue in eubacterial L7/L12-type proteins point to the functional implication of this arginine residue.
