Solution conformation and properties of the galactoglucan from Rhizobium meliloti strain YE-2(S1).
The physicochemical solution properties of the galactoglucan excreted by Rhizobium meliloti strain YE-2(S1) have been investigated by capillary viscometry, potentiometric titration, isothermal mixing microcalorimetry, and circular dichroism. Potentiometric and chiro-optical data, as a function of the degree of ionisation, indicate the absence of a co-operative conformational transition. Solution properties, as a function of ionic strength and temperature, suggest that the galactoglucan adopts a disordered conformation characterised by moderate flexibility. Polyelectrolyte theory is used to fit the enthalpy of dilution data with a suitable linear charge-density parameter. Conformational calculations and chain modelling, using molecular mechanics, give an unperturbed characteristic ratio, (C infinity) of 20, which was smaller than that estimated from intrinsic-viscosity and molecular-weight data for an expanded-coil chain model.
Cesàro
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Department of Biochemistry, Biophysics, and Macromolecular Chemistry, University of Trieste, Italy.
Tomasi
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Gamini
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Vidotto
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Navarini
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D002151:Calorimetry; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002942:Circular Dichroism; D007202:Indicators and Reagents; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009904:Optical Rotation; D011135:Polysaccharides, Bacterial / Q000737:chemistry* / Q000302:isolation & purification; D011199:Potentiometry; D016962:Sinorhizobium meliloti / Q000737:chemistry*; D012996:Solutions
D007202:Indicators and Reagents; D011135:Polysaccharides, Bacterial; D012996:Solutions