1,721,046 research outputs found
La moderna medicina molecolare nell’era post-genomica e le sue radici nell’antica Universitas. Annali della Scuola Medica Salernitana
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A four- to sixfold enhancement in sensitivity for detecting trace proteins in dye or silver stained polyacrylamide gels.
No full textA very simple procedure which enhances sensitivity in visualizing proteins stained by all standard procedures in polyacrylamide gels is described. The process, based on the use of concentrated polyethylene glycol 6000 solutions, produces a conspicuous, reversible, and uniform size reduction of gels. The entity of the reduction depends principally on the polyethylene glycol 6000 concentration and on the acrylamide content of gels. Using an appropriate polyethylene glycol 6000 concentration, it is possible to regulate the final size and then the sensitivity as needed. Depending upon the above conditions it is possible to increase the sensitivity by a factor of 4-6 or more. Reduction of the gel volume by such a factor may eliminate the need for the cumbersome and frequently impossible preconcentration of samples. Besides the Coomassie blue stained gels, silver stained gels may also be treated in a similar manner with a consequent further enhancement in sensitivity. In addition, gels containing radiolabeled materials can be autoradiographed in times proportionally shorter, without significant sacrifice of resolution
High-yield and high-degree purification of human alpha-fetoprotein produced by adaptation of the human hepatoma cell line Hep G2 in a serum-free medium.
No full textThe human hepatoma cell line Hep G2 secretes both albumin and alpha-fetoprotein when grown in the presence of serum. The present report describes how adaptation to growth in serum-free medium results in a progressive switch in the expression of the two proteins; i.e., alpha-fetoprotein becomes the main protein secreted while albumin production is greatly reduced. The culture supernatant obtained, being very enriched in the protein, allows the development of a purification procedure by preparative electrophoresis. By this procedure it is possible to easily obtain large amounts of alpha-fetoprotein from a constant and unlimited source. The availability of these protein preparations should improve the reproducibility and the quality of standardization in clinical immunoassays for alpha-fetoprotein and should permit a more accurate study of the structure and biological functions of the protein
Thyroid hormone effect on alpha-fetoprotein and albumin coordinate expression by a human hepatoma cell line.
No full textThe action of triiodothyronine on the production of alpha-fetoprotein and albumin in serum-free cultures of Hep G2 human hepatoma cells was examined. Our data showed that a marked inhibition (up to 8-fold) of alpha-fetoprotein secretion and an increase in albumin (up to 4-fold) are produced by 10(-8) M triiodothyronine. These effects were slow in their onset and for completion required 20-25 days of treatment with the hormone. However, an exposure of the cells to triiodothyronine for only the first 4 h was sufficient to affect, in a similar way, the secretion of alpha-fetoprotein and albumin when measured 15 days after treatment. The secretion of the two proteins parallels their intracellular levels. The decrease in alpha-fetoprotein production can be explained by a reduction of the RNA coding for the protein. The same is essentially true also for albumin increased secretion and related mRNA expression
Molecular effects of docosahexaenoic acid on carcinogenesis and tumor progression processes
No full textIodine-induced changes in thyroglobulin half-sized subunits.
No full textThe two half-sized subunits of 19 S thyroglobulin have been separated and analyzed. They share the same peptide composition and carbohydrate content. The only difference was the iodine level, which was about three times higher in the faster electrophoretic subunit
Molecular organization of 19 S calf thyroglobulin.
No full textControlled freezing and thawing of 19 S calf thyroglobulin resulted in a specific and reproducible breakdown of the protein. Beside the elementary chain (300,000 Da), new, discrete bands are revealed by gel electrophoresis in sodium dodecyl sulfate under reducing conditions. These new species consist of a major peptide of 100,000 Da and several faster-migrating bands. Most of these polypeptides were purified by preparative gel electrophoresis and individually digested in formic acid with CNBr. A comparative gel electrophoresis under denaturating and reducing conditions of (i) the fragments obtained from the native protein, (ii) the electrophoretically purified elementary chain, (iii) the 100,000-Da peptide, and (iv) a smaller fragment (of about 50,000) was performed. It revealed a very close homology among the peptide maps of the intact 19 S, the elementary chain, and the 100,000-Da peptide. Furthermore, it was shown that the digestion products of the smaller fragment, present in the peptide map of the native protein, were absent in both the elementary chain and the 100,000-Da species. These results support the idea that calf thyroglobulin, even though it has an apparently complex molecular organization, contains structural motifs which are repeated in the elementary chain
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