Abstract：
:The most popular pretreatment method of plasma samples for the measurement of ascorbate (AsA) and dehydroascorbate (DHA) has been an acidic deproteinization via metaphosphoric acid or trichloroacetic acid. In general, DHA is absent in plasma samples prepared from human blood in a conventional manner. However, when these plasma samples were subjected to acidic deproteinization, DHA was detected in the acidified sample solutions. In the present study, we demonstrate that the oxidation of AsA to DHA in the solutions was promoted by at least two mechanisms, one involving catalysis by ferric ion released from transferrin, and the other involving catalysis by plasma hemoglobin. In the acidified transferrin solution by trichloroacetic acid, an oxidation of AsA to DHA proceeded with standing time, whereas the oxidation was not observed in that by metaphosphoric acid. This oxidation appeared to be catalyzed by ferric ion released from transferrin. In contrast, plasma hemoglobin functioned as a catalyst for AsA oxidation in both metaphosphoric acid and trichloroacetic acid solutions. Therefore, DHA content in the trichloroacetic acid-treated plasma sample was markedly higher than that in the metaphosphoric acid-treated one. These results suggest that DHA detected in acidified plasma samples is an artifact resulting from AsA oxidation.
journal_name
Clin Chemjournal_title
Clinical chemistryauthors
Koshiishi I,Mamura Y,Liu J,Imanari Tsubject
Has Abstractpub_date
1998-04-01 00:00:00pages
863-8issue
4eissn
0009-9147issn
1530-8561journal_volume
44pub_type
杂志文章abstract：:We describe an enzymic assay for the functional activity of alpha 1-antitrypsin, in which tosyl-Gly-Pro-Lys-p-nitroanilide acetate (Chromozym PL) is the trypsin substrate. For the indicating reaction, the concentration of substrate is about double the Km of its reaction with trypsin. This assay is an improvement over ...
journal_title：Clinical chemistry
pub_type： 杂志文章
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更新日期：1984-11-01 00:00:00
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journal_title：Clinical chemistry
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doi：
更新日期：1988-12-01 00:00:00
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journal_title：Clinical chemistry
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更新日期：1996-03-01 00:00:00
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journal_title：Clinical chemistry
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journal_title：Clinical chemistry
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更新日期：2001-04-01 00:00:00
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更新日期：1978-01-01 00:00:00
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doi：
更新日期：1979-07-01 00:00:00
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doi：
更新日期：1986-05-01 00:00:00
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journal_title：Clinical chemistry
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doi：
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journal_title：Clinical chemistry
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doi：
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journal_title：Clinical chemistry
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doi：
更新日期：1995-05-01 00:00:00
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journal_title：Clinical chemistry
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doi：
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doi：
更新日期：1985-03-01 00:00:00
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更新日期：1999-09-01 00:00:00
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journal_title：Clinical chemistry
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doi：
更新日期：1988-06-01 00:00:00
