One-step purification method for pyridylamino glycans.
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Pyridylamino derivatization is suitable for the microanalysis of glycans but there is a problem in that by-products of the labeling reaction and fluorescent substances from samples occasionally interfere with the detection of pyridylamino glycans. We have reported a three-step purification method (S. Natsuka et al., FEBS J., 278, 452-460 (2011)). That method gives high purity and high yield for various glycans, but it is rather complicated. In this study I checked the efficiency of a one-step method with a spin column for the purification of pyridylamino glycans and found that it was excellent in respect of throughput. High-throughput analysis of N-glycans is desirable in glycomics. (+info)
Fetuin-A, type 2 diabetes, and risk of cardiovascular disease in older adults: the cardiovascular health study.
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Accelerated evolution of fetuin family proteins in Protobothrops flavoviridis (habu snake) serum and the discovery of an L1-like genomic element in the intronic sequence of a fetuin-encoding gene.
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Habu serum factor (HSF) and HSF-like protein (HLP) are fetuin family proteins isolated from Protobothrops flavoviridis (habu snake) serum with different physiological activities. A comparison of their cDNAs and intronic sequences revealed that nucleotide substitutions were primarily in protein-coding regions, and the substitution patterns indicated accelerated evolution of these proteins. Genomic DNA fragment analysis, including intron 1, revealed a 6.6-kb insertion homologous to the full-length mammalian LINE1 (L1) retrotransposable element (PfL1) only in the HLP gene. This segment retains an open reading frame (ORF) that encodes a reverse transcriptase (RT)-like protein (PfRT). We further found that a large number of homologous segments have dispersed in the habu snake genome, although we could not determine the enzymatic activities of their products. Moreover, an analysis of habu snake liver RNA indicated active transcription of the PfRT genes, suggesting that high levels of RT activity in this snake have driven the evolution of unique phenotypes of venom enzymes and serum inhibitors of them. (+info)
Biochemical characterization of a polysialyltransferase from Mannheimia haemolytica A2 and comparison to other bacterial polysialyltransferases.
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The effects of monensin on secretion of very-low-density lipoprotein and metabolism of asialofetuin by cultured rat hepatocytes.
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Primary cultures of rat hepatocytes were used to study secretion of very-low-density lipoproteins and metabolism of asialofetuin. The ionophore monensin inhibited both secretion of very-low-density lipoproteins and binding and degradation of asialofetuin in a concentration-dependent manner. Secretion as well as receptor binding were markedly decreased after 15 min treatment with monensin. The inhibitory effect of the ionophore was fully reversible, and no effect on protein synthesis was observed at concentrations up to 50 microM. The secretion of apoproteins (B-small, B-large and E) and that of albumin were inhibited to the same extent as was triacylglycerol secretion. Secretion of very-low-density lipoproteins was more sensitive to low concentrations of monensin than was the metabolism of asialofetuin. Maximum inhibition of very-low-density-lipoprotein secretion was obtained at 5-10 microM-monensin, whereas 25 microM was required to obtain maximum inhibition of binding and degradation of asialofetuin. The number of surface receptors for asialofetuin decreased to about half when the cells were exposed to 25 microM-monensin. It is possible that monensin inhibits endo- and exo-cytosis via a similar mechanism, e.g. by disturbing proton gradients. Since secretion of very-low-density lipoproteins was more sensitive to low concentrations of monensin, it is likely that monensin independently inhibits endocytic and secretory functions in cultured hepatocytes. (+info)