Protein stability changes of the novel p.Arg180Cys mutant A glycosyltransferase resulted in a weak A phenotype.

A novel A subgroup allele (c.538C>T p.Arg180Cys) showing weak A phenotype was found in a 30-year-old Korean woman with ABO discrepancy. Using 3D structural analysis, protein stability prediction and flow cytometric analysis of ABO antigen expression on HeLa cells transfected with plasmids containing the p.Arg180Cys mutant, we found that the Arg180 residue in the loop region of the A glycosyltransferases (GTA) structure plays significant role in stabilizing its closed conformation, which is required for substrate binding and catalysis study.

A novel cis-AB variant allele arising from a de novo nucleotide substitution c.796A>G (p.M266V) in the B glycosyltransferase gene.

BACKGROUND: Cis-AB, a rare ABO variant, is the result of a mutated ABO gene that produces a glycosyltransferase enzyme with dual A and B glycosyltransferase activity. It may lead to ABO discrepancies and a delay in establishing the blood group. To date, there have been no reports of a de novo mutation leading to a cis-AB allele. OBJECTIVES AND METHODS: Sequencing of the ABO gene using blood and hair follicle cells from the proposita were performed along with blood from her parents. To establish maternity and paternity, short tandem repeat (STR) analysis was also performed. The A and B enzyme activities of the novel enzyme were measured in an in vitro expression study. RESULTS: A novel cis-AB allele arising from nucleotide substitution c.796A>G (p.M266V) in the B glycosyltransferase gene were discovered in the blood and hair follicle cells from the proposita, which was absent from her parents. In all 15 autosomal STR loci analysed, the probability of maternity and paternity were 0.999999 and 0.999989, respectively. The novel enzyme created 33.1% and 60.2% of A and B antigen compared to wild type A and B glycosyltransferases. CONCLUSION: A novel mechanism leading to a cis-AB allele was discovered.

Dissolution profiles of flurbiprofen in phospholipid solid dispersions.

This study is concerned with the development of a solid dispersion formulation of flurbiprofen (FLP) and phospholipid (PL) with improved dissolution characteristics. The FLP powders were blended with PL to produce FLP-PL physical mixtures or made into solid dispersions with PL by the solvent method. The FLP exhibited significantly improved dissolution rates in PL coprecipitate (coppt) compared to the physical mixtures or FLP alone. The dissolution studies suggested that less than a 20:1 ratio of FLP to PL was required to disperse FLP completely in the carrier. The coppt yielded a ninefold greater initial dissolution rate. Also, the total amount dissolved after 60 min was twofold greater at a 10:1 ratio of FLP to L-(-dimyristoyl phosphatidylglycerol (DMPG). Similar results were observed with a ratio as low as 20:1 (FLP:DMPG). Increasing the DMPG content did not increase the rate to any significant extent. Thus, a small PL:FLP ratio improved the dissolution to a significant level. Thus, an FLP:PL dispersion may have the clinical advantages of quick release and excellent bioavailability.