%0 Journal Article %1 CHRISTENSEN1993a %A CHRISTENSEN, B. E. %A KNUDSEN, K. D. %A SMIDSROD, O. %A KITAMURA, S. %A TAKEO, K. %C 605 THIRD AVE, NEW YORK, NY 10158-0012 %D 1993 %I JOHN WILEY & SONS INC %J Biopolymers %K ;; [ISI:] aqueous bacterial behavior electron-microscopy; polysaccharide; sodium-chloride; %N 1 %P 151 -- 161 %T TEMPERATURE-INDUCED CONFORMATIONAL TRANSITION IN XANTHANS WITH PARTIALLY HYDROLYZED SIDE-CHAINS %V 33 %X The conformational properties of xanthans with partially hydrolyzed side chains were investigated by optical rotation, CD, and differential scanning calorimetry (DSC). All variants displayed the well-known temperature-driven, cooperative order-disorder transition, and both optical rotation and DSC showed that the transition temperature was essentially independent of the content of terminal beta-mannose. It was found that up to 80% of the changes in the specific optical rotation accompanying the transition reflects conformational changes linked to the terminal beta-mannose in the side chains. Modification of the side chains also affected the CD when xanthan was in the ordered state, but in this case the data suggest that the glucuronic acid is the major component determining the magnitude of the CD signal. DSC measurements showed that the transition enthalpy (DELTAH(cal)) increased linearly with the fraction of beta-mannose, again indicating that a significant part (up to 80%) of DELTAH(cal) reflects conformational changes in the side chains. The conformational transition of the xanthan variants generally showed a higher degree of cooperativity (sharper transition) than unmodified, pyruvated xanthan. Calculation of the cooperativity parameter sigma by means of the Zimm-Bragg theory (OR data) or from the ratio between DELTAH(cal) and the van't Hoff enthalpy (DELTAH(v)H) Using DSC data showed a correlation between sigma and the content of beta-mannose, but the two methods gave different results when the content of beta-mannose approached 100%. The ionic strength dependence of the transition temperature, expressed as d(log I)/d(T(m)-1), was nearly identical for intact xanthan and a sample containing only 6% of the terminal beta-mannose. Application of the Manning polyelectrolyte theory does not readily account for the observed DELTAH(cal) values, neither does it provide new information on the nature of the ordered and disordered conformations in xanthan.

@article{CHRISTENSEN1993a, __markedentry = {[phpts:6]}, abstract = {The conformational properties of xanthans with partially hydrolyzed side chains were investigated by optical rotation, CD, and differential scanning calorimetry (DSC). All variants displayed the well-known temperature-driven, cooperative order-disorder transition, and both optical rotation and DSC showed that the transition temperature was essentially independent of the content of terminal beta-mannose. It was found that up to 80% of the changes in the specific optical rotation accompanying the transition reflects conformational changes linked to the terminal beta-mannose in the side chains. Modification of the side chains also affected the CD when xanthan was in the ordered state, but in this case the data suggest that the glucuronic acid is the major component determining the magnitude of the CD signal. DSC measurements showed that the transition enthalpy (DELTAH(cal)) increased linearly with the fraction of beta-mannose, again indicating that a significant part (up to 80%) of DELTAH(cal) reflects conformational changes in the side chains. The conformational transition of the xanthan variants generally showed a higher degree of cooperativity (sharper transition) than unmodified, pyruvated xanthan. Calculation of the cooperativity parameter sigma by means of the Zimm-Bragg theory (OR data) or from the ratio between DELTAH(cal) and the van't Hoff enthalpy (DELTAH(v)H) Using DSC data showed a correlation between sigma and the content of beta-mannose, but the two methods gave different results when the content of beta-mannose approached 100%. The ionic strength dependence of the transition temperature, expressed as d(log I)/d(T(m)-1), was nearly identical for intact xanthan and a sample containing only 6% of the terminal beta-mannose. Application of the Manning polyelectrolyte theory does not readily account for the observed DELTAH(cal) values, neither does it provide new information on the nature of the ordered and disordered conformations in xanthan.}, added-at = {2011-11-04T13:47:04.000+0100}, address = {605 THIRD AVE, NEW YORK, NY 10158-0012}, author = {CHRISTENSEN, B. E. and KNUDSEN, K. D. and SMIDSROD, O. and KITAMURA, S. and TAKEO, K.}, authoraddress = {KYOTO PREFECTURAL UNIV,DEPT AGR CHEM,SAKYO KU,KYOTO 606,JAPAN.}, biburl = {https://www.bibsonomy.org/bibtex/27316d89b36608ea520dff7757e9e3e87/pawelsikorski}, citedref = {BEMILLER JN, 1967, ADV CARBOHYD CHEM, V22, P25 ; CANTOR CR, 1980, BIOPHYSICAL CHEM 3 ; CHRISTENSEN BE, 1984, CARBOHYD RES, V214, P1771 ; DENTINI M, 1984, INT J BIOL MACROMOL, V6, P93 ; DISCHE Z, 1962, METHODS CARBOHYDR CH, V1, P497 ; HACCHE LS, 1987, MACROMOLECULES, V20, P2179 ; HOLZWARTH G, 1976, BIOCHEMISTRY-US, V15, P4333 ; HOLZWARTH G, 1979, CARBOHYD RES, V76, P277 ; KAWAKAMI K, 1991, CARBOHYD POLYM, V14, P189 ; KITAMURA S, 1991, BIOPOLYMERS, V31, P1243 ; LIU W, 1987, CARBOHYD RES, V160, P267 ; LIU W, 1988, INT J BIOL MACROMOL, V10, P44 ; MANNING GS, 1987, IND POLYSACCHARIDES, P305 ; MILAS M, 1979, CARBOHYD RES, V76, P189 ; MORRIS ER, 1977, J MOL BIOL, V110, P1 ; NORTON IT, 1984, J MOL BIOL, V175, P371 ; PAOLETTI S, 1983, CARBOHYD RES, V123, P173 ; PAOLETTI S, 1984, BIOPOLYMERS, V23, P1771 ; PRIVALOV PL, 1980, PURE APPL CHEM, V52, P479 ; REES DA, 1970, NATURE, V227, P390 ; SATO T, 1985, POLYM J, V17, P729 ; STODDART JF, 1971, STEREOCHEMISTRY CARB ; STOKKE BT, 1986, INT J BIOL MACROMOL, V8, P217 ; STOKKE BT, 1987, CARBOHYD RES, V160, P13 ; STOKKE BT, 1989, ACS SYM SER, V396, P145 ; STOKKE BT, 1989, BIOPOLYMERS, V28, P617 ; STOKKE BT, 1991, J APPL POLYM SCI, V42, P2063 ; STURTEVANT JM, 1987, ANNU REV PHYS CHEM, V38, P463 ; SUTHERLAND IW, 1984, CARBOHYD RES, V131, P93 ; TAIT MI, 1990, CARBOHYD POLYM, V13, P133 ; TAKAHASHI K, 1981, BIOCHEMISTRY-US, V20, P6185}, interhash = {c035d7a80b6bee7609aae00120be76c9}, intrahash = {7316d89b36608ea520dff7757e9e3e87}, isifile-dt = {Article}, isifile-ga = {KF712}, isifile-j9 = {BIOPOLYMERS}, isifile-nr = {31}, isifile-pi = {NEW YORK}, isifile-rp = {CHRISTENSEN, BE, UNIV TRONDHEIM,NTH,DEPT BIOTECHNOL,NORWEGIAN ; BIOPOLYMER LAB,N-7034 TRONDHEIM,NORWAY.}, isifile-sc = {Biochemistry & Molecular Biology; Biophysics}, isifile-tc = {16}, issn = {0006-3525}, journal = {Biopolymers}, keywords = {;; [ISI:] aqueous bacterial behavior electron-microscopy; polysaccharide; sodium-chloride;}, language = {English}, month = JAN, number = 1, owner = {phpts}, pages = {151 -- 161}, publisher = {JOHN WILEY \& SONS INC}, size = {11 p.}, sourceid = {ISI:A1993KF71200014}, timestamp = {2011-11-04T13:47:07.000+0100}, title = {TEMPERATURE-INDUCED CONFORMATIONAL TRANSITION IN XANTHANS WITH PARTIALLY HYDROLYZED SIDE-CHAINS}, volume = 33, year = 1993 }