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phosphate and three nearly equally charged oxygens (0-11, 0-12, 0-21) which could partake in ionic binding or hydrogen bonding, or perhaps as general acid-base agents for the ylide protonation deprotonation step. The pyrophosphate charge may also be used in maintaining the Mg(I1) metal in its required position. Further theoretical work on the mechanism of binding as well as a conformational analysis of the dimethylene pyrophosphate side chain will be reported later. The need for further experimental work on the
definition of the solution conformation of the coenzyme as well as on the details of the enzyme-coenzyme-substrate interactions is obvious. Acknowledgment. Computer time was generously provided by the Rutgers University Center for Computer and Information Services. The experimental work, on which preliminary results were discussed, was supported in part by the Rutgers University Research Council.
Topography of Cyclodextrin Inclusion Complexes. 111. Crystal and Molecular Structure of Cyclohexaamylose Hexahydrate, the (H,O), Inclusion Complex’ Philip C. Manor and Wolfram Saenger* Contribution f r o m Max-Planck-Institut f ur Experimentelle Medizin, Abteilung Chemie, 34 Gottingen, Germany. Received September 29, 1973
Abstract: Cyclohexaamylose, a-cyclodextrin, is a torus-shaped cyctic hexasaccharide consisting of n-(l 44)linked glucopyranose residues. Due to the annular aperture 4.5-5.5 A in diameter in the center of the molecule it is able to form inclusion complexes with a variety of substrate molecules even in aqueous solution. Cyclohexaamylose hexahydrate, the (H20)2inc@ion comple
