Reference Table for Serum and Plasma Enzyme Sources-EnkiLife-Recombinant Proteins,Antibodies,Kits,Cell Biology

Reference Table for Serum and Plasma Enzyme Sources

The core principle of ELISA experiments is the specific binding of antigens and antibodies, while endogenous enzymes in samples can non-specifically catalyze substrate reactions or destroy antigen/antibody structures, leading to abnormal experimental signals and interference. Many customers often encounter issues such as biased test results, false positives or false negatives when conducting ELISA experiments, due to the failure to clarify the sources of various enzymes in the samples and add enzyme inhibitors in a targeted manner. To help customers accurately avoid this experimental pain point and efficiently complete ELISA experiments, EnkiLife has compiled the "Serum and Plasma Enzyme Source Reference Table", while combining core experimental needs to popularize the sources of serum and plasma enzymes and their association with ELISA experimental interference, helping everyone exclude interference and ensure reliable experimental results by clarifying enzyme sources and rationally adding enzyme inhibitors.

Enzyme Category	Representative Enzymes (Common Members)	Main Sources (Cells/Tissues)	Distribution Characteristics in Serum vs. Plasma	Recommended Inhibitors (Specific dosage should follow manufacturer's instructions)
Serine Proteases	Thrombin, Plasmin, Trypsin, Elastase	• Platelets release multiple zymogens • Neutrophils are the main source of elastase • Hepatocytes synthesize coagulation factor precursors (e.g., fibrinogen) • Vascular endothelial cells secrete cathepsins and kallikrein	Serum: Platelets are activated during coagulation, releasing large amounts of active serine proteases, resulting in significantly increased activity. Plasma: Due to the addition of anticoagulants such as EDTA/citrate that inhibit the coagulation cascade, enzyme activity is relatively low.	Aprotinin Leupeptin PMSF (prepared on ice) AEBSF α1-antitrypsin (α1AT) Protease Inhibitor Cocktail
Cysteine Proteases	Cathepsin B, Cathepsin H, Cathepsin L, Cathepsin S	• Macrophages and monocytes contain numerous lysosomes • Neutrophils • Platelets	Serum: Lysosomes are rich in Cathepsins, and these cells release zymogens or active enzymes into the blood when activated or undergoing apoptosis. Additionally, platelets can release small amounts of cysteine proteases when activated. Plasma: Anticoagulants prevent cell rupture, resulting in even lower enzyme activity.	E-64 Leupeptin Protease Inhibitor Cocktail
Matrix Metalloproteinases (MMPs)	MMP2, MMP9, ADAMTS13	• Platelets • Macrophages/monocytes/neutrophils • Endothelial cells	Serum: Platelets release large amounts of MMP-2/MMP9 when activated, resulting in significantly increased activity. Plasma: Metal chelators such as EDTA inhibit metalloenzyme activity, resulting in relatively lower concentrations.	EDTA EGTA (specifically inhibits Ca²⁺-dependent metalloenzymes) 1,10-Phenantroline DTPA
Aspartic Proteases	Pepsin, Renin, Cathepsin D	• Kidney (juxtaglomerular cells) • Liver • Macrophages	Serum: Blood coagulation can cause platelet rupture, potentially releasing some intracellular zymogens. Plasma: Due to the use of anticoagulants, blood cells remain intact, resulting in less release of intracellular zymogens.	Pepstatin A Protease Inhibitor Cocktail
Aminopeptidases	Aminopeptidase N (APN, CD13), Leucine Aminopeptidase (LAP), Aminopeptidase A (APA)	• Platelets (main source) • Leukocytes • Red blood cells	Serum: During the coagulation process, platelets release large amounts of zymogens, which are activated into active enzymes after centrifugation. Plasma: The addition of anticoagulants such as EDTA or heparin can effectively inhibit platelet aggregation, significantly reducing the release of platelet-derived aminopeptidases.	Bestatin Amastatin 4,7-Dimethyl-1,10-phenanthroline EDTA
Phosphatases	Acid Phosphatase (ACP), Alkaline Phosphatase (ALP), Protein Tyrosine Phosphatases (PTPs)	• Platelets • Leukocytes (especially neutrophils)	Due to blood coagulation, platelets are activated and release their granular contents. Platelets are rich in acid phosphatase, so acid phosphatase activity in serum is typically higher than in plasma.	Na₃VO₄ NaF
Kinases	Tyrosine Kinases, Serine/Threonine Kinases, Complex Kinases	• Platelets • Leukocytes • Vascular endothelial cells	Serum: Platelets release a specific cAMP-dependent protein kinase (PKA) after stimulation, which can phosphorylate specific proteins in serum. Plasma: Platelet-poor plasma (PPP) typically does not contain platelet-released active PKA, but may contain low levels of other kinases or zymogens.	Staurosporine (broad-spectrum kinase inhibitor) Protease and Phosphatase Inhibitor Cocktail
Lipases / Phospholipases	Pancreatic Lipase, Lipoprotein Lipase (LPL), Phospholipase A2 (PLA2), Phospholipase C (PLC)	• Platelets (main source of PLA₂) • Vascular endothelial cells • Pancreas (main source of pancreatic lipase)	Serum: PLA₂ is released in large amounts after platelet activation, resulting in increased activity. Plasma: Anticoagulants inhibit platelet activation, resulting in relatively lower activity.	Orlistat Methyl indoxam Varespladib
Glycosidases	β-Galactosidase, β-N-Acetylglucosaminidase, α-Mannosidase	• Platelets • Leukocytes	Serum: During the blood coagulation process, β-glucosidase is released when platelets are activated. Plasma: Platelets are inhibited, resulting in significantly reduced release of β-glucosidase.	Deoxynojirimycin, DNJ PUGNAc Castanospermine

Finally, it is important to remind everyone that although there are clear conventional references for the sources of serum and plasma enzymes, the normal range of enzyme activity and source interpretation need to be combined with specific scenarios due to factors such as individual differences, detection methods, and sample processing methods.

In the future, we will continue to update ELISA experiment-related content, providing more comprehensive and practical reference materials to help everyone better carry out scientific research experiments.