PubMed · 74784
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L Uziel, S A Cederholm-Williams. Measuring plasminogen activator.. https://doi.org/10.1016/s0140-6736(77)90431-7
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Peroxidase-deficient mutants of the lignin-degrading bacterium Streptomyces viridosporus T7A were screened for their production of acid-precipitable polymeric lignin, extracellular peroxidases and esterases, and immunoreactivities against a polyclonal antibody produced against electrophoretically purified peroxidase isoform P3 of wild-type S. viridosporus. The mutants showed diminished abilities to solubilize lignin and produce acid-precipitable polymeric lignin. Their peroxidase activities were decreased, and their esterase production patterns were altered. Western immunoblots demonstrated that the mutants produced proteins immunologically reactive with the antibody, but with different mobilities from those of wild-type proteins. These findings confirm a direct role for peroxidases in lignin solubilization. They also indicate a possible role for esterases.
Bovine serum albumin was modified with activated PEG2, 2,4-bis[O-methoxypoly(ethylene glycol)]-6-chloro-s-triazine. The PEG-modified albumin, in which 15 out of the total 60 amino groups in the albumin molecule were coupled with activated PEG2, lost immunoreactivity towards anti-albumin serum and retained 63% of the esterase activity of native albumin.
Many assay techniques have been used to measure lipid hydroperoxides in plasma, including absorbance of conjugated dienes and reactivity with thiobarbituric acid. Because these measurements are not specific for lipid hydroperoxides, we modified an exisiting iodometric method to correct for interfering phenomena and to provide a more specific measurement of the lipid hydroperoxide content of plasma. To ensure reproducible extraction of hydroperoxides from the many possible forms in plasma, the plasma was treated to hydrolyze enzymatically cholesterol ester, triglycerides, and phospholipids, and the nonesterified fatty acid peroxides were then extracted with ethyl acetate. Extracted lipids were reacted with potassium iodide in acetic acid and methylene chloride, and the resulting triiodide ion (I3-) was measured spectrophotometrically. Correction for nonoxidizing chromophores was made after back-titration of the triiodide ion to iodide with sodium thiosulfate and other non-peroxide oxidants were estimated by their resistance to reduction with glutathione peroxidase. Recovery of added hydroperoxide standards provided routine validations of the procedure's efficiency. The method indicated that insignificant amounts of hydroperoxide may be in the less polar lipids, but the total amount of lipid hydroperoxide esterfied in the plasma lipids of apparently healthy humans may be as much as 4.0 +/- 1.7 microM.