Product Name:	Human Cathepsin B (CTSB) ELISA Kit
Product Code:	HUEB0183
Alias:	Cathepsin B, APP secretase, APPS, Cathepsin B1, CTSB, CPSB, 3.4.22.1
Uniprot:	P07858
Reactivity:	Human
Range:	0.312-20 ng/ml
Detection Method:	Sandwich
Size:	96 Assay
Storage:	Please see kit components below for exact storage details
Note:	For research use only

UniProt Protein Function:	CTSB: Thiol protease which is believed to participate in intracellular degradation and turnover of proteins. Has also been implicated in tumor invasion and metastasis. Dimer of a heavy chain and a light chain cross-linked by a disulfide bond. Interacts with SRPX2. Belongs to the peptidase C1 family.
UniProt Protein Details:	Protein type:Motility/polarity/chemotaxis; Protease; Autophagy; EC 3.4.22.1 Chromosomal Location of Human Ortholog: 8p22 Cellular Component: apical plasma membrane; caveola; external side of plasma membrane; extracellular region; extracellular space; intracellular; intracellular membrane-bound organelle; lysosome; melanosome; mitochondrion; nucleolus; perinuclear region of cytoplasm; sarcolemma Molecular Function:collagen binding; cysteine-type endopeptidase activity; cysteine-type peptidase activity; kininogen binding; peptidase activity; peptide binding; protein binding; protein self-association; proteoglycan binding Biological Process: autophagy; collagen catabolic process; decidualization; entry of virus into host cell; epithelial cell differentiation; extracellular matrix disassembly; extracellular matrix organization and biogenesis; innate immune response; proteolysis; proteolysis involved in cellular protein catabolic process; regulation of apoptosis; regulation of catalytic activity; response to amine stimulus; response to ethanol; response to glucose stimulus; response to organic cyclic substance; response to peptide hormone stimulus; response to wounding; skeletal muscle development; spermatogenesis; toll-like receptor signaling pathway
NCBI Summary:	This gene encodes a member of the C1 family of peptidases. Alternative splicing of this gene results in multiple transcript variants. At least one of these variants encodes a preproprotein that is proteolytically processed to generate multiple protein products. These products include the cathepsin B light and heavy chains, which can dimerize to form the double chain form of the enzyme. This enzyme is a lysosomal cysteine protease with both endopeptidase and exopeptidase activity that may play a role in protein turnover. It is also known as amyloid precursor protein secretase and is involved in the proteolytic processing of amyloid precursor protein (APP). Incomplete proteolytic processing of APP has been suggested to be a causative factor in Alzheimer's disease, the most common cause of dementia. Overexpression of the encoded protein has been associated with esophageal adenocarcinoma and other tumors. Multiple pseudogenes of this gene have been identified. [provided by RefSeq, Nov 2015]
UniProt Code:	P07858
NCBI GenInfo Identifier:	68067549
NCBI Gene ID:	1508
NCBI Accession:	P07858.3
UniProt Secondary Accession:	P07858,Q503A6, Q96D87, B3KQR5, B3KRR5,
UniProt Related Accession:	P07858
Molecular Weight:	37,822 Da
NCBI Full Name:	Cathepsin B
NCBI Synonym Full Names:	cathepsin B
NCBI Official Symbol:	CTSB
NCBI Official Synonym Symbols:	APPS; CPSB
NCBI Protein Information:	cathepsin B
UniProt Protein Name:	Cathepsin B
UniProt Synonym Protein Names:	APP secretase; APPS
Protein Family:	Cathepsin
UniProt Gene Name:	CTSB
UniProt Entry Name:	CATB_HUMAN

Component	Quantity (96 Assays)	Storage
ELISA Microplate (Dismountable)	8×12 strips	-20°C
Lyophilized Standard	2	-20°C
Sample Diluent	20ml	-20°C
Assay Diluent A	10mL	-20°C
Assay Diluent B	10mL	-20°C
Detection Reagent A	120µL	-20°C
Detection Reagent B	120µL	-20°C
Wash Buffer	30mL	4°C
Substrate	10mL	4°C
Stop Solution	10mL	4°C
Plate Sealer	5	-

Other materials and equipment required:

Microplate reader with 450 nm wavelength filter
Multichannel Pipette, Pipette, microcentrifuge tubes and disposable pipette tips
Incubator
Deionized or distilled water
Absorbent paper
Buffer resevoir

*Note: The below protocol is a sample protocol. Protocols are specific to each batch/lot. For the correct instructions please follow the protocol included in your kit.

Allow all reagents to reach room temperature (Please do not dissolve the reagents at 37°C directly). All the reagents should be mixed thoroughly by gently swirling before pipetting. Avoid foaming. Keep appropriate numbers of strips for 1 experiment and remove extra strips from microtiter plate. Removed strips should be resealed and stored at -20°C until the kits expiry date. Prepare all reagents, working standards and samples as directed in the previous sections. Please predict the concentration before assaying. If values for these are not within the range of the standard curve, users must determine the optimal sample dilutions for their experiments. We recommend running all samples in duplicate.

Step
1.	Add Sample: Add 100µL of Standard, Blank, or Sample per well. The blank well is added with Sample diluent. Solutions are added to the bottom of micro ELISA plate well, avoid inside wall touching and foaming as possible. Mix it gently. Cover the plate with sealer we provided. Incubate for 120 minutes at 37°C.
2.	Remove the liquid from each well, don't wash. Add 100µL of Detection Reagent A working solution to each well. Cover with the Plate sealer. Gently tap the plate to ensure thorough mixing. Incubate for 1 hour at 37°C. Note: if Detection Reagent A appears cloudy warm to room temperature until solution is uniform.
3.	Aspirate each well and wash, repeating the process three times. Wash by filling each well with Wash Buffer (approximately 400µL) (a squirt bottle, multi-channel pipette,manifold dispenser or automated washer are needed). Complete removal of liquid at each step is essential. After the last wash, completely remove remaining Wash Buffer by aspirating or decanting. Invert the plate and pat it against thick clean absorbent paper.
4.	Add 100µL of Detection Reagent B working solution to each well. Cover with the Plate sealer. Incubate for 60 minutes at 37°C.
5.	Repeat the wash process for five times as conducted in step 3.
6.	Add 90µL of Substrate Solution to each well. Cover with a new Plate sealer and incubate for 10-20 minutes at 37°C. Protect the plate from light. The reaction time can be shortened or extended according to the actual color change, but this should not exceed more than 30 minutes. When apparent gradient appears in standard wells, user should terminatethe reaction.
7.	Add 50µL of Stop Solution to each well. If color change does not appear uniform, gently tap the plate to ensure thorough mixing.
8.	Determine the optical density (OD value) of each well at once, using a micro-plate reader set to 450 nm. User should open the micro-plate reader in advance, preheat the instrument, and set the testing parameters.
9.	After experiment, store all reagents according to the specified storage temperature respectively until their expiry.

When carrying out an ELISA assay it is important to prepare your samples in order to achieve the best possible results. Below we have a list of procedures for the preparation of samples for different sample types.

Sample Type	Protocol
Serum	If using serum separator tubes, allow samples to clot for 30 minutes at room temperature. Centrifuge for 10 minutes at 1,000x g. Collect the serum fraction and assay promptly or aliquot and store the samples at -80°C. Avoid multiple freeze-thaw cycles. If serum separator tubes are not being used, allow samples to clot overnight at 2-8°C. Centrifuge for 10 minutes at 1,000x g. Remove serum and assay promptly or aliquot and store the samples at -80°C. Avoid multiple freeze-thaw cycles.
Plasma	Collect plasma using EDTA or heparin as an anticoagulant. Centrifuge samples at 4°C for 15 mins at 1000 × g within 30 mins of collection. Collect the plasma fraction and assay promptly or aliquot and store the samples at -80°C. Avoid multiple freeze-thaw cycles. Note: Over haemolysed samples are not suitable for use with this kit.
Urine & Cerebrospinal Fluid	Collect the urine (mid-stream) in a sterile container, centrifuge for 20 mins at 2000-3000 rpm. Remove supernatant and assay immediately. If any precipitation is detected, repeat the centrifugation step. A similar protocol can be used for cerebrospinal fluid.
Cell culture supernatant	Collect the cell culture media by pipette, followed by centrifugation at 4°C for 20 mins at 1500 rpm. Collect the clear supernatant and assay immediately.
Cell lysates	Solubilize cells in lysis buffer and allow to sit on ice for 30 minutes. Centrifuge tubes at 14,000 x g for 5 minutes to remove insoluble material. Aliquot the supernatant into a new tube and discard the remaining whole cell extract. Quantify total protein concentration using a total protein assay. Assay immediately or aliquot and store at ≤ -20 °C.
Tissue homogenates	The preparation of tissue homogenates will vary depending upon tissue type. Rinse tissue with 1X PBS to remove excess blood & homogenize in 20ml of 1X PBS (including protease inhibitors) and store overnight at ≤ -20°C. Two freeze-thaw cycles are required to break the cell membranes. To further disrupt the cell membranes you can sonicate the samples. Centrifuge homogenates for 5 mins at 5000xg. Remove the supernatant and assay immediately or aliquot and store at -20°C or -80°C.
Tissue lysates	Rinse tissue with PBS, cut into 1-2 mm pieces, and homogenize with a tissue homogenizer in PBS. Add an equal volume of RIPA buffer containing protease inhibitors and lyse tissues at room temperature for 30 minutes with gentle agitation. Centrifuge to remove debris. Quantify total protein concentration using a total protein assay. Assay immediately or aliquot and store at ≤ -20 °C.
Breast Milk	Collect milk samples and centrifuge at 10,000 x g for 60 min at 4°C. Aliquot the supernatant and assay. For long term use, store samples at -80°C. Minimize freeze/thaw cycles.