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- Hult, Annika, et al.
(author)
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Weak A phenotypes associated with novel ABO alleles carrying the A(2)-related 1061C deletion and various missense substitutions.
- 2010
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In: Transfusion. - : Wiley. - 1537-2995 .- 0041-1132. ; 50, s. 1471-1486
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Journal article (peer-reviewed)abstract
- BACKGROUND: The 1061delC single-nucleotide polymorphism (SNP) has been reported mostly in the context of the common A(2)[A201] allele and typically produces an A(2) phenotype. This study evaluated new A(weak) alleles, each containing 1061delC. STUDY DESIGN AND METHODS: Twenty samples were referred to our laboratory for analysis due to suspected A(weak) phenotypes originally detected at the referring centers. ABO Exons 1 through 7 and flanking intronic regions were sequenced. A antigen expression on red blood cells was analyzed by flow cytometry. Plasma enzyme activity was studied in one case. Molecular three-dimensional modeling techniques studied the potential effects of amino acid changes on the resulting glycosyltransferases (GTs). RESULTS: Thirteen alleles were discovered, each featuring 1061delC with at least 1 of 12 additional SNPs in the coding region. One of these SNPs disrupts the translation initiation codon. Another constitutes the first reported change in the DVD motif. One SNP found in three alleles causes a substitution of one of the four amino acids that differentiates the wild-type A and B enzymes but plasma enzyme analysis by two methods showed only slightly decreased or normal A(2) activity. Flow cytometric analysis semiquantified the A antigen levels in 16 cases featuring 10 of the alleles and ranged from very weak to nearly A(2) levels. However, the majority of the samples displayed A(x)-like patterns. Molecular modeling of some of the GT variants indicated conformational changes that may explain the diminished A expression observed. CONCLUSION: Missense SNPs were identified in 13 novel A(2)-like alleles, which produced a variety of A subgroup phenotypes.
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| 2. |
- Rademacher, Christoph, et al.
(author)
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NMR-based exploration of the acceptor binding site of human blood group B galactosyltransferase with molecular fragments
- 2010
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In: Glycoconjugate Journal. - : Springer. - 0282-0080 .- 1573-4986. ; 27:3, s. 349-358
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Journal article (peer-reviewed)abstract
- A substantial body of work has been devoted to the design and synthesis of glycosyltransferase inhibitors. A major obstacle has always been the demanding chemistry. Therefore, only few potent and selective inhibitors are known to date. Glycosyltransferases possess two distinct binding sites, one for the donor substrate, and one for the acceptor substrate. In many cases binding to the donor site is well defined but data for acceptor binding is sparse. In particular, acceptor binding sites are often shallow, and in many cases the dimensions of the binding pocket are not well defined. One approach to glycosyltransferase inhibitors is to chemically link donor site and acceptor site ligands to generate high affinity binders. Here, we describe a novel approach to identify acceptor site ligands from a fragment library. We have chosen human blood group B galactosyltransferase (GTB) as a biologically important model target. The approach utilizes a combination of STD NMR, spin-lock filtered NMR experiments and surface plasmon resonance measurements. Following this route we have identified molecular fragments from a fragment library that bind to the acceptor site of GTB with affinities of the order of a natural acceptor substrate. Unlike natural substrates these fragments allow for straightforward chemical modifications and, therefore will serve as scaffolds for potent GTB inhibitors. In general, the approach described is applicable to any glycosyltransferase and may assist in the development of novel glycosyltransferase inhibitors.
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