Biomaterial Database

X-ray diffraction studies on the structure of alpha-chitin. 1976

M A Haleem, and K D Parker

The structure for alpha-chitin originally proposed by Carlström is generally considered to be the true structure. However, it fails to account for several remaining problems of chitin structure which include a complete explanation of the infrared spectrum and also the different properties of alpha- and beta-chitins. We have reexamined the structure by X-ray diffraction using automatic rigid subunit least-squares refinement and also the difference Fourier method. The R-value was reduced from 0.31 to 0.22 by a number of small modifications to the structure proposed by Carlström. Consideration of symmetry suggests that two distinct types of statistical modifications could be present in the structure, both of which would allow complete intersheet hydrogen bonding between O6H groups within the general framework of Carlström structure. The X-ray results give some support to one of these modifications. However, it is predictable that both would affect the X-ray diffraction only marginally so that a clear proof lies beyond the present sensitivity of the method. The proposed extra hydrogen bonding in alpha-chitin provide the first clear explanation for the different properties of these kinds of chitin.

UI	MeSH Term	Description	Entries
D008968	Molecular Conformation	The characteristic three-dimensional shape of a molecule.	Molecular Configuration,3D Molecular Structure,Configuration, Molecular,Molecular Structure, Three Dimensional,Three Dimensional Molecular Structure,3D Molecular Structures,Configurations, Molecular,Conformation, Molecular,Conformations, Molecular,Molecular Configurations,Molecular Conformations,Molecular Structure, 3D,Molecular Structures, 3D,Structure, 3D Molecular,Structures, 3D Molecular
D002686	Chitin	A linear polysaccharide of beta-1->4 linked units of ACETYLGLUCOSAMINE. It is the second most abundant biopolymer on earth, found especially in INSECTS and FUNGI. When deacetylated it is called CHITOSAN.
D003386	Brachyura	An infraorder of chiefly marine, largely carnivorous CRUSTACEA, in the order DECAPODA, including the genera Cancer, Uca, and Callinectes.	Blue Crab,Callinectes sapidus,Carcinus maenas,Crab, Blue,Crab, Common Shore,Crab, Green,Crabs, Short-Tailed,Crabs, True,Green Crab,Uca,Common Shore Crab,European Shore Crab,Blue Crabs,Brachyuras,Carcinus maena,Common Shore Crabs,Crab, European Shore,Crab, Short-Tailed,Crab, True,Crabs, Blue,Crabs, Common Shore,Crabs, Green,Crabs, Short Tailed,Green Crabs,Shore Crab, Common,Shore Crab, European,Shore Crabs, Common,Short-Tailed Crab,Short-Tailed Crabs,True Crab,True Crabs,Ucas,maenas, Carcinus
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013710	Tendons	Fibrous bands or cords of CONNECTIVE TISSUE at the ends of SKELETAL MUSCLE FIBERS that serve to attach the MUSCLES to bones and other structures.	Endotenon,Epotenon,Tendons, Para-Articular,Tendons, Paraarticular,Endotenons,Epotenons,Para-Articular Tendon,Para-Articular Tendons,Paraarticular Tendon,Paraarticular Tendons,Tendon,Tendon, Para-Articular,Tendon, Paraarticular,Tendons, Para Articular
D014961	X-Ray Diffraction	The scattering of x-rays by matter, especially crystals, with accompanying variation in intensity due to interference effects. Analysis of the crystal structure of materials is performed by passing x-rays through them and registering the diffraction image of the rays (CRYSTALLOGRAPHY, X-RAY). (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Xray Diffraction,Diffraction, X-Ray,Diffraction, Xray,Diffractions, X-Ray,Diffractions, Xray,X Ray Diffraction,X-Ray Diffractions,Xray Diffractions