Introduction
Cathepsin D, an estrogen-regulated lysosomal protease, plays a crucial role in cancer cell migration and invasion. It achieves this by breaking down the basement membrane, extracellular matrix, and connective tissue. Its involvement in these processes, along with its mitogenic activities, has led to its recognition as a potential prognostic marker for various cancer types. Cathepsin D is found in both epithelial cells and macrophages. The protein is initially synthesized as a 54kDa precursor, which undergoes proteolytic processing to form a 48kDa intermediate single chain. This intermediate then matures into a more stable two-chain form consisting of 34kDa and 14kDa units.
Description
CTSD, produced in Sf9 Baculovirus cells, is a single, glycosylated polypeptide chain with a molecular mass of 44.0kDa. The protein consists of 398 amino acids (specifically, amino acids 21 to 410) and appears on SDS-PAGE at a size of approximately 40-57kDa. This CTSD variant includes an 8 amino acid His tag at its C-terminus and is purified using proprietary chromatographic techniques.
Physical Appearance
Clear, colorless solution that has been sterilized by filtration.
Formulation
The CTSD protein solution is provided at a concentration of 0.25mg/ml. It is formulated in a solution of Phosphate Buffered Saline (pH 7.4) and 10% glycerol.
Stability
For short-term storage (up to 2-4 weeks), the CTSD protein solution should be stored at 4°C. For extended storage, it is recommended to freeze the solution at -20°C. To further ensure stability during long-term storage, consider adding a carrier protein such as HSA or BSA (0.1% concentration). It is crucial to minimize the number of freeze-thaw cycles to maintain protein integrity.
Purity
The purity of CTSD is greater than 90%, as determined by SDS-PAGE analysis.
Biological Activity
CTSD exhibits a specific activity greater than 1,000 pmol/min/µg. This indicates that one unit of the enzyme can convert 1.0 picomole of the substrate Mca-PLGL-Dpa-AR-NH2 to the product MCA-Pro-Leu-OH within one minute. This activity is measured at a pH of 3.5 and a temperature of 25°C.
Synonyms
Ctsd, CatD, CD, Cathepsin D.
Source
Sf9, Baculovirus cells.
Amino Acid Sequence
IIRIPLRKFT SIRRTMTEVG GSVEDLILKG PITKYSMQSS PKTTEPVSEL
LKNYLDAQYY GDIGIGTPPQ CFTVVFDTGS SNLWVPSIHC KILDIACWVH HKYNSDKSST YVKNGTSFDI
HYGSGSLSGY LSQDTVSVPC KSDQSKARGI KVEKQIFGEA TKQPGIVFVA AKFDGILGMG YPHISVNNVL
PVFDNLMQQK LVDKNIFSFY LNRDPEGQPG GELMLGGTDS KYYHGELSYL NVTRKAYWQV HMDQLEVGNE
LTLCKGGCEA IVDTGTSLLV GPVEEVKELQ KAIGAVPLIQ GEYMIPCEKV SSLPTVYLKL GGKNYELHPD
KYILKVSQGG KTICLSGFMG MDIPPPSGPL WILGDVFIGS YYTVFDRDNN RVGFANAVVL LEHHHHHH.