PubMed · 14101461
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M ARAKAWA, H TADA. 1963. [GALACTOSEMIA].. https://pubmed.ncbi.nlm.nih.gov/14101461/
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Phosphatidylcholine (PC) is an important and abundant structural component of the membranes of eukaryotic cells. In the yeast Saccharomyces cerevisiae, the primary route for the biosynthesis of PC consists of three consecutive methylation steps of phosphatidylethanolamine (PE) catalyzed by the phospholipid N-methyltransferases Cho2p and Opi3p. To investigate how these biosynthetic enzymes contribute to the composition of the PC species profile, the precursor-product relationships between PE and newly synthesized PC were determined at the level of the molecular species by using electrospray ionization tandem mass spectrometry and stable isotope labeling. In vivo labeling of yeast cells for 10 min with [methyl-D3]methionine revealed the preferential methylation of di-C16:1 PE over a range of PE species compositions. A similar preferential conversion of di-C16:1 PE to PC was found in vitro upon incubating isolated microsomes with S-adenosyl[methyl-D3]methionine. Yeast opi3 and cho2 deletion strains were used to distinguish between the substrate selectivities of Cho2p and Opi3p, respectively. Both biosynthetic enzymes were found to participate in the speciesselective methylation with Cho2p contributing the most. The combined results indicate that the selective methylation of PE species by the methyltransferases plays an important role in shaping the steady-state profile of PC molecular species in yeast.
The lipase from Candida rugosa (Sigma) was used to catalyze the regioselective deacetylation at the 5-position of 1,2,3,5-tetra-O-acetyl-beta-D-ribofuranose on a preparative scale. Enzymatic deacetylation provides a convenient one-step preparation of 1,2,3-tri-O-acetyl-beta-D-ribofuranose.
Bioinformatics has played a pivotal role in advancing genetics and protein sciences. The large amount of information generated by genomics, and now proteomics, has been a driving force. By comparison, glycobiology still generates small amounts of data. The need to organize our knowledge about carbohydrates is however growing constantly and has given rise to an increasing number of public databases and freely available tools. This review gives an overview of the carbohydrate-oriented resources currently available on the Internet. Many of the resources are seldom referred to in the literature and difficult to find, in part because of the constant flux of the net itself, but also because many efforts have been lead by a single individual. As the World Wide Web has matured the number of 'permanent' resources, maintained by organizations rather than individuals, has increased. In this paper, we present some of the more useful and accessible public tools and databases. There are also a few commercial initiatives but these have not been reviewed.