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Literature summary extracted from

  • Sim, R.B.
    The human complement system serine proteases C1bar and C1sbar and their proenzymes (1981), Methods Enzymol., 80, 26-42.
    View publication on PubMed

General Stability

EC Number General Stability Organism
3.4.21.42 stable at concentrations of 1-2 mg/ml Homo sapiens

Inhibitors

EC Number Inhibitors Comment Organism Structure
3.4.21.41 4-Nitrophenyl-4-guanidinobenzoate
-
 Homo sapiens
3.4.21.41 C1bar-inhibitor irreversible Homo sapiens
3.4.21.41 diisopropyl fluorophosphate
-
 Homo sapiens
3.4.21.41 leupeptin competitive Homo sapiens
3.4.21.41 NaCl above 200 mM Homo sapiens
3.4.21.42 amidines
-
 Homo sapiens
3.4.21.42 C1bar inhibitor
-
 Homo sapiens
3.4.21.42 DFP
-
 Homo sapiens
3.4.21.42 Guanidines
-
 Homo sapiens
3.4.21.42 p-nitrophenyl-p'-guanidinobenzoate
-
 Homo sapiens

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
3.4.21.41 20
-
 acetyl-Gly-Lys methyl ester
-
 Homo sapiens
3.4.21.42 0.056 0.07 N-benzyloxycarbonyl-Tyr p-nitrophenyl ester
-
 Homo sapiens
3.4.21.42 0.8
-
 N-benzyloxycarbonyl-Lys p-nitrophenyl ester
-
 Homo sapiens
3.4.21.42 1.7 2.8 tosyl-Arg methyl ester
-
 Homo sapiens
3.4.21.42 2.5 5 benzoyl-Arg ethyl ester
-
 Homo sapiens
3.4.21.42 19
-
 acetyl-L-Tyr ethyl ester
-
 Homo sapiens

Molecular Weight [Da]

EC Number Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
3.4.21.41 85000
-
 2 * 85000, the C1rbar subunits consist of one polypeptide chain of 56000 Da, A-chain, that is disulfide-linked to a 27000 Da B-chain, SDS-PAGE Homo sapiens
3.4.21.42 27000
-
 x * 56000, A chain, + x * 27000, B chain, gel filtration under denaturing conditions Homo sapiens
3.4.21.42 56000
-
 x * 56000, A chain, + x * 27000, B chain, gel filtration under denaturing conditions Homo sapiens

Natural Substrates/ Products (Substrates)

EC Number Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
3.4.21.41 complement component C1s Homo sapiens activates the proenzyme form of C1s by limited proteolysis ?
-
 ?
3.4.21.42 additional information Homo sapiens binding of C1 to certain viral activators occurs through both C1s and C1q ?
-
 ?

Organism

EC Number Organism UniProt Comment Textmining
3.4.21.41 Homo sapiens
-
-
-
3.4.21.42 Homo sapiens
-
-
-

Posttranslational Modification

EC Number Posttranslational Modification Comment Organism
3.4.21.41 proteolytic modification the proenzyme is C1r Homo sapiens
3.4.21.41 proteolytic modification activation of the proenzyme C1r can be mimicked under certain conditions by digestion of C1r with trypsin or plasmin Homo sapiens
3.4.21.41 side-chain modification C1rbar contains about 40 carbohydrate residues per molecule Homo sapiens
3.4.21.41 side-chain modification the zymogen C1r is a glycoprotein Homo sapiens
3.4.21.42 proteolytic modification C1rbar cleaves a single Arg-Ile or Lys-Ile bond in proenzyme C1s Homo sapiens
3.4.21.42 proteolytic modification C1s is the proenzyme of C1sbar Homo sapiens
3.4.21.42 side-chain modification C1sbar A chain contains 6.5% carbohydrate per weight, C1sbar B chain contains 7.5% carbohydrate per weight Homo sapiens

Purification (Commentary)

EC Number Purification (Comment) Organism
3.4.21.41
-
 Homo sapiens
3.4.21.42 C1s and C1sbar Homo sapiens

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
3.4.21.41 acetyl-Arg methyl ester + H2O
-
 Homo sapiens acetyl-Arg + methanol
-
 ?
3.4.21.41 complement component C1s activates the proenzyme form of C1s by limited proteolysis Homo sapiens ?
-
 ?
3.4.21.41 complement component C1s + H2O cleavage of a single Arg-Ile or Lys-Ile bond in C1s Homo sapiens complement component C1sbar
-
 ?
3.4.21.41 N-acetyl-Gly-Lys methyl ester + H2O
-
 Homo sapiens N-acetyl-Gly-Lys + methanol
-
 ?
3.4.21.42 Benzoyl-Arg ethyl ester + H2O
-
 Homo sapiens ?
-
 ?
3.4.21.42 complement component C2 + H2O cleavage of a single bond, likely to be Lys-Lys or Arg-Lys Homo sapiens complement component C2a + complement component C2b
-
 ?
3.4.21.42 complement component C4 + H2O cleavage of a single Arg-Ala bond in the sequence Leu-Gln-Arg-Ala-Leu-Glu Homo sapiens complement component C4a + complement component C4b
-
 ?
3.4.21.42 additional information binding of C1 to certain viral activators occurs through both C1s and C1q Homo sapiens ?
-
 ?
3.4.21.42 N-benzyloxycarbonyl-Lys-p-nitrophenyl ester + H2O N-alpha-benzyloxycarbonyl-L-Lys p-nitrophenyl ester Homo sapiens ?
-
 ?
3.4.21.42 N-benzyloxycarbonyl-Tyr-p-nitrophenyl ester + H2O
-
 Homo sapiens ?
-
 ?
3.4.21.42 Nalpha-acetyl-Tyr ethyl ester + H2O
-
 Homo sapiens ?
-
 ?
3.4.21.42 Nalpha-tosyl-Arg methyl ester + H2O
-
 Homo sapiens ?
-
 ?
3.4.21.42 Tosyl-Arg methyl ester + H2O
-
 Homo sapiens ?
-
 ?

Subunits

EC Number Subunits Comment Organism
3.4.21.41 dimer 2 * 85000, the C1rbar subunits consist of one polypeptide chain of 56000 Da, A-chain, that is disulfide-linked to a 27000 Da B-chain, SDS-PAGE Homo sapiens
3.4.21.41 More on activation the single polypeptide chain of C1r is cleaved probably at a single position, the C1rbar subunits consist of 1 polypeptide chain of 56000 Da, A-chain, that is disulfide-linked to a 27000 Da B-chain Homo sapiens
3.4.21.42 ? x * 56000, A chain, + x * 27000, B chain, gel filtration under denaturing conditions Homo sapiens

Temperature Stability [°C]

EC Number Temperature Stability Minimum [°C] Temperature Stability Maximum [°C] Comment Organism
3.4.21.42 56
-
 30 min, 50% loss of activity Homo sapiens

pH Optimum

EC Number pH Optimum Minimum pH Optimum Maximum Comment Organism
3.4.21.41 7.5 8.5
-
 Homo sapiens
3.4.21.42 7 8.5 acetyl-Tyr ethyl ester Homo sapiens

pH Stability

EC Number pH Stability pH Stability Maximum Comment Organism
3.4.21.42 5 9.5 4°C, irreversible inactivation below pH 5.0 and above pH 9.5, overnight exposure Homo sapiens