PolySacDb

A Database of Polysachharide 3D structures

 
By A. Sarkar & S. Pérez
 
 
 

Polysaccharides For Experts

Carrageenan Iota

 

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Diffraction Diagram

   

Fig.1 The fibres were tilted out of the plane normal to the X-ray beam 10° in order to record the 003 reflecrion (0.443 nm spacing). The specimen-to-film distance was approx. 30 mm. Exposure times were 23 h for the (Ca2+salt and 11 h for the Sr2 + salt). The relative humidky was maintained at 75%. Fibre diffraction patterns of the :

(a)Fibre diffraction patterns of the Ca2+ i-carrageenate.

(b)Fibre diffraction patterns of the Sr2+ i-carrageenate.

   

Fig.2  Fibre diffraction patterns of the Mg2+ i-carrageenate:

(a)The normal type obtained from a fibre prepared under slow drying conditions.

(b)The unusual type with interleaving Iayer lines obtained from fibres prepared under rapid drying conditions.

*Permission Pending for Diffraction Diagrams

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Structures are best viewed using PyMol & Sybyl

(Please download the structure and view in a stand-alone viewer if the structure appears distorted in Jmol)

 

  Carrageenan Iota

Linkage :       beta 1-4      beta 1-3

 

Space Group :       trigonal P3212

 

Unit Cell Dimensions (a, b, c in Å and α, β, γ in °)

(No values are displayed if no information is available or the value is zero)

a (Å) =   13.73

b (Å) =   13.73

c (Å) =   13.28

 

γ (°) =   120.00

 

Helix Type :      

two, identical, right. handed, 3-fold helical polysaccharide chains

 

Method(s) Used For Structure Determination :      

X-ray diffraction

 

Link to the Abstract :      
 
http://www.ncbi.nlm.nih.gov/pubmed/4453016

 

Reference :      

Iota-carrageenan: molecular structure and packing of polysaccharide double helices in oriented fibres of divalent cation salts
Arnott, S., Scott, W.E., Rees, D.A. and McNab, C.G.A., J. Mol. Biol. 1974, 90, 253-267

 

 

Download Structure

Unit          carrageenan-iota_expanded

 

 

 

 

 
   
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