THE ENZYMATIC NATURE OF C'1r
| Autor: | Oscar D. Ratnoff, George B. Naff |
|---|---|
| Rok vydání: | 1968 |
| Předmět: |
medicine.medical_treatment
Protein subunit Immunology Hemolysis Esterase Article Hydrolysis Zymogen medicine Humans Immunology and Allergy Amino Acids chemistry.chemical_classification Enzyme Precursors Protease Kunitz STI protease inhibitor Esterases Temperature Esters Complement System Proteins Hydrogen-Ion Concentration Amino acid Enzyme chemistry Biochemistry Peptide Hydrolases |
| Zdroj: | The Journal of Experimental Medicine |
| ISSN: | 1540-9538 0022-1007 |
| DOI: | 10.1084/jem.128.4.571 |
| Popis: | Human C'1, a macromolecular complex composed of three subunits, is the zymogen for at least two distinct enzymes. Preparations of one subunit, C'1r, functioned as a protease which converted another subunit, C'1s, to C'1 esterase. The conversion of C'1s to C'1 esterase by C'1r was blocked by Liquoid, phenyl methylsulfonyl fluoride, and calcium ions, but not by soybean trypsin inhibitor, hirudin, or heparin. Preparations of C'1r also possessed two additional functions, i.e., the ability to hydrolyze certain synthetic amino acid esters and to participate in immune hemolysis. Evidence was presented which indicates that these three functions are properties of a single entity, C'1r, but not of the same portion of its molecular structure. These observations suggest that C'1r has at least two active sites, one for its reaction with C'1q, an additional subunit of C'1, and one for its reaction with C'1s; together, the three subcomponents, C'1q, C'1r, and C'1s, form a single functional unit, the first component of complement. |
| Databáze: | OpenAIRE |
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