alpha 1-Cysteine proteinase inhibitor was isolated from normal and acute phase rat serum. The procedure, which includes successive fractionations on AcA 34, Cibacron blue Sepharose, DEAE-Sephacel, and hydroxyapatite, but avoids the use of an affinity chromatography step on a cysteine proteinase gel, led to the preparation of two electrophoretically distinct components. These resolved to a single band of apparent Mr = 68,000 when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A slightly higher Mr was estimated from gel filtration studies, possibly related to the rather high carbohydrate content (15.25% of the dry weight). The purified protein exhibited strong inhibiting capacity towards papain with a Ki of 5 X 10(-11) M. As shown by immunochemical quantitation as well as functional activity, a 6-10-fold increase in the alpha 1-cysteine cysteine proteinase inhibitor content was recorded in inflammatory serum, thus demonstrating the protein to be a typical acute phase reactant. Its partial physicochemical characterization (Mr, isoelectric point, extinction coefficient, amino acid and carbohydrate compositions) shows large similarities with alpha 1 acute phase globulin whose biological function remains unknown, and which is present at the same concentration (about 0.5 g/liter) in normal serum. Identity between the two molecules has been further demonstrated by double immunodiffusion analysis since a continuous precipitating line was observed when purified alpha 1-cysteine proteinase inhibitor was reacted against anti-alpha 1 acute phase globulin and anti-alpha 1-cysteine cysteine proteinase inhibitor antibodies.
Rat alpha 1-cysteine proteinase inhibitor. An acute phase reactant identical with alpha 1 acute phase globulin.
Published 1983 in Journal of Biological Chemistry
ABSTRACT
PUBLICATION RECORD
- Publication year
1983
- Venue
Journal of Biological Chemistry
- Publication date
1983-10-25
- Fields of study
Biology, Medicine, Chemistry
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
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