Maltose conformers

In connection with the crystallographic work a primitive conformational analysis was carried out, with results inferior to our 16 S 215 

Tvaroska made a simulation of maltose in various solvents Based on coordinates gotten from us, he estimated the influence of changing solvent properties on relative conformer populations. One interesting result is that in many solvents a more balanced population is expected than what is calculated for the naked molecule. Our l68 

4-0-p-D-glucopyranosyl-p-D-glucopyranose, which also was structurally well-known, and for which we expected slightly more 

The switch to PEF400 caused a very neat bracketing of the crystal 

When the first calculations were made, there were essentially no experimental data available for comparison. Due to the very flexible glycosidic linkage, many minima were found, certainly not all, hopefully all those of low energy. For the same reason, it is difficult to make a good crystal. 

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Fig.3. Repeating the "cis (=maltose) conformation results in a helical structure while the "trans" (=cellobiose) leads to a zig-zag chain.

Maltose, l- 4- -link in, 998 molecular model of, 998 mutarotation of, 998 structure of, 998 Manicone, synthesis of. 805 Mannich reaction. 915 Mannose, biosynthesis of, 1011 chair conformation of, 126 configuration of, 982 molecular model of, 126 Margarine, manufacture of, 1063 Markovnikov. Vladimir Vassilyevich. 192... 

Figure 5. Conformational map for maltose, calculated with MMP2(85), using the methods that are described in the chapter herein by French, Tran and P6rez with four starting models. < ) and f were varied in steps of 20 . Contours are at intervals of one kcal/mol.

Figure 10. Relaxed (adiabatic) conformational energy map for p-maltose as computed by Brady and coworkers.i3 Contours are drawn at 2,4,6, 8, and 10 kcal/mol above the minimum near < ), y = -60°, -40°. The p-maltose structure may be derived from that of p-cellobiose in Fig. 1 by inversion of the stereochemical configuration at Cl.

When determining the range of likely helical shapes from intrinsic properties of amylose, this variability in monomer shape is almost as important as hindered rotation about the bonds linking the monomers. This conclusion is supported by conformational analyses of maltose such as shown in Figure 5 of the introductory chapter of this book. There are relatively small ranges (about 40 ) of allowed torsional rotation within one kcal/mol of the minimum (one must correct for the fact that there are two glucose residues in maltose when making such a coiqparison). ... 

A short presentation of the Consistent Force Field is given, with emphasis on parametrization and optimization of energy function parameters. For best possible calculation of structure, potential energy functions with parameter values optimized on both structural and other properties must be used. Results from optimization with the Consistent Force Field on alkanes and ethers are applied to glucose, gentiobiose, maltose and cellobiose. Comparison is made with earlier and with parallel work. The meaning and use of conformational maps is discussed shortly. 

French has recently presented comparisons of rigid and relaxed conformational maps for cellobiose and maltose obtained with the MMP2(1985), which includes ano-meric effects. The fully relaxed maps show interesting details. 

Figure 3. Conformational Map of Maltose. + PEF300, X PEF400, o PEFACl, D MMP2...

This valley is investigated in some detail in the original paper on maltose (10) where also references to experimental work can be found. Some details are given in Table IV it is noteworthy that in PEFACl one conformer is dominant, which is in agreement with the results of PEF400 (3,10). 

Nallamsetty S, Waugh DS. (2007) Mutations that alter the equilibrium between open and closed conformations of Escherichia coli maltose-binding protein impede its ability to enhance the solubility of passenger proteins. Biochem Biophys Res Commun 364, 639-44. 

Favored conformations of maltose arrived at by free-energy calculations were in good agreement with those for the solid state and in solution.17-18 From thermal-expansibility experiments, it has been suggested that, in aqueous solution, the maltose molecule folds, and undergoes extensive, intramolecular, hydrophobic bonding.19... 

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