Recombinant Human Complement MASP3 Catalytic Domain, CF Summary
Details of Functionality
Measured by its ability to cleave a colorimetric peptide substrate, N-carbobenzyloxy-Lys-ThioBenzyl ester (Z-Lys-SBzl), in the presence of 5,5’Dithio-bis (2-nitrobenzoic acid) (DTNB). Edwards, K.M. et al. (1999) J. Biol. Chem. 274:30468. The specific activity is >10,000 pmol/min/µg, as measured under the described conditions.
Mouse myeloma cell line, NS0-derived human Complement Factor MASP3 protein Ile450-Val721, with an N-terminal signal peptide and a C-terminal 10-His tag
>95%, by SDS-PAGE under reducing conditions and visualized by silver stain.
<1.0 EU per 1 μg of the protein by the LAL method.
31 kDa. Disclaimer note: The observed molecular weight of the protein may vary from the listed predicted molecular weight due to post translational modifications, post translation cleavages, relative charges, and other experimental factors.
43 kDa, reducing conditions
Read Publication using 1724-SE in the following applications:
Substrate: Z-Lys-SBzl (Bachem, Catalog # M-1300), 10 mM stock in DMSO
5,5'-dithio-bis (2-nitrobenzoic acid) (DTNB) (Sigma, Catalog # D-8130), 10 mM stock in DMSO
UV-transparent 96 Well Microplate (Corning, Catalog # 3635)
Plate reader (Model: SpectraMax Plus by Molecular Devices) or equivalent
Dilute rhMASP3 to 0.04 ng/µL in Assay Buffer.
Combine equal volumes of 10 mM Substrate and 10 mM DTNB for 5 mM of each.
Dilute Substrate/DTNB mixture to 200 µM of each with Assay Buffer.
Load 50 µL of the 0.04 ng/µL rhMASP3 into a UV plate, and start the reaction by adding 50 µL of 200 µM Substrate. Include a Substrate Blank containing 50 µL Assay Buffer and 50 μL of 200 µM Substrate without any rhMASP3.
Read at a wavelength of 405 nm (bottom read) in kinetic mode for 5 minutes.
Calculate specific activity:
Specific Activity (pmol/min/µg) =
Adjusted Vmax* (OD/min) x well volume (L) x 1012 pmol/mol
ext. coeff** (M-1cm-1) x path corr.*** (cm) x amount of enzyme (µg)
*Adjusted for Substrate Blank **Using the extinction coefficient 13260 M-1cm-1 ***Using the path correction 0.320 cm Note: the output of many spectrophotometers is in mOD. Per Well:
rhMASP3: 0.002 µg
Substrate: 100 µM
DTNB: 100 µM
This product is produced by and ships from R&D Systems, Inc., a Bio-Techne brand.
Alternate Names for Recombinant Human Complement MASP3 Catalytic Domain, CF
Complement Factor MASP3
Complement factor MASP-3
Complement-activating component of Ra-reactive factor
MASP3 is a member of the MASPs involved in mannan-binding lectin (MBL) complement pathway (1). The MBL pathway is initiated by the binding of MBL to specific carbohydrate structures found on the surface of a variety of microorganisms. Activation of the complement pathway via MBL is initiated by specific MASPs. Three MASPs have been identified and all have domain structures similar to those of C1r and C1s with a heavy chain (chain A) and a light chain (chain B). Chain A is composed of CUB1, EGF, CUB2, CCP1 and CCP2 while chain B corresponds to the catalytic domain found in many serine proteases. MASP1 and MASP3 are two alternatively spliced products of a single gene, which contain the same A chains but entirely different B chains. Distinct MASPs found in different MBL oligomers may have different biological activities. For example, MASP3, found together with MASP2, downregulates the C4 and C2 cleaving activity of MASP2. The protease activity of MASP3 is first revealed here using recombinant human MASP3CD (2), which is inhibited by serine protease inhibitors such as ecotin and AEBSF (Catalog # 1328-PI and EI001).
Dahl, M.R. et al. (2001) Immunity 15:127.
Cortesio, C.L. and W. Jiang (2006) Arch. Biochem. Biophys. 449:164.
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