| 1. |
- Broadhurst, Edward T., et al.
(författare)
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Polymorph evolution during crystal growth studied by 3D electron diffraction
- 2020
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Ingår i: IUCrJ. - 2052-2525. ; 7, s. 5-9
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Tidskriftsartikel (refereegranskat)abstract
- 3D electron diffraction (3DED) has been used to follow polymorph evolution in the crystallization of glycine from aqueous solution. The three polymorphs of glycine which exist under ambient conditions follow the stability order beta < alpha < gamma. The least stable beta polymorph forms within the first 3 min, but this begins to yield the alpha-form after only 1 min more. Both structures could be determined from continuous rotation electron diffraction data collected in less than 20 s on crystals of thickness similar to 100 nm. Even though the gamma-form is thermodynamically the most stable polymorph, kinetics favour the alpha-form, which dominates after prolonged standing. In the same sample, some beta and one crystallite of the gamma polymorph were also observed.
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| 3. |
- Liu, Qiyong P, et al.
(författare)
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Identification of a GH110 subfamily of alpha 1,3-galactosidases - Novel enzymes for removal of the alpha 3Gal xenotransplantation antigen
- 2008
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 283:13, s. 8545-8554
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Tidskriftsartikel (refereegranskat)abstract
- In search of alpha-galactosidases with improved kinetic properties for removal of the immunodominant alpha 1,3-linked galactose residues of blood group B antigens, we recently identified a novel prokaryotic family of alpha-galactosidases (CAZy GH110) with highly restricted substrate specificity and neutral pH optimum (Liu, Q. P., Sulzenbacher, G., Yuan, H., Bennett, E. P., Pietz, G., Saunders, K., Spence, J., Nudelman, E., Levery, S. B., White, T., Neveu, J. M., Lane, W. S., Bourne, Y., Olsson, M. L., Henrissat, B., and Clausen, H. (2007) Nat. Biotechnol. 25, 454-464). One member of this family from Bacteroides fragilis had exquisite substrate specificity for the branched blood group B structure Gal alpha 1-3(Fuc alpha 1-2) Gal, whereas linear oligosaccharides terminated by alpha 1,3-linked galactose such as the immunodominant xenotransplantation epitope Gal alpha 1-3Gal beta 1-4GlcNAc did not serve as substrates. Here we demonstrate the existence of two distinct subfamilies of GH110 in B. fragilis and thetaiotaomicron strains. Members of one subfamily have exclusive specificity for the branched blood group B structures, whereas members of a newly identified subfamily represent linkage specific alpha 1,3-galactosidases that act equally well on both branched blood group B and linear alpha 1,3Gal structures. We determined by one-dimensional H-1 NMR spectroscopy that GH110 enzymes function with an inverting mechanism, which is in striking contrast to all other known alpha-galactosidases that use a retaining mechanism. The novel GH110 subfamily offers enzymes with highly improved performance in enzymatic removal of the immunodominant alpha 3Gal xenotransplantation epitope.
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