Cytochrome C ELISA Kit (CYCS)

Full Name: Cytochrome C ELISA Kit (CYCS)
Reactivity: Human
Sample Type: Plasma, Tissue Homogenates, Serum, Biological Fluids
Sensitivity: 0.094 ng/ml


Cytochrome C (CYCS) is best known for its role in apoptosis, but it also functions as an essential component of the electron transport chain enabling aerobic respiration. This hemeprotein functions as a reducing agent that accepts and donates single electrons as it interconverts between its reduced and oxidized states. Neighboring cytochrome c oxidase and cytochrome c reductase drive this alternating reduction and oxidation using the proton gradient across the inner mitochondrial membrane.

With a highly conserved structure across eukaryotes, CYCS shuttles electrons from Complex III to Complex IV in the respiratory chain. This couples the redox reactions downstream from coenzyme Q to molecular oxygen reduction, pumping protons outward through the membrane per transferred electron. Thereby CYCS facilitates the ultimate transfer of electrons to oxygen while concomitantly storing energy as the proton motive force. This electrochemical gradient powers ATP synthase and generates the cellular fuel ATP. Hence CYCS enables aerobic ATP synthesis essential for meeting energy demands.

Beyond energy production, CYCS also mediates intrinsic apoptosis signaling. Once released from mitochondria, it binds apoptotic protease activating factor-1, triggering the caspase cascade. This proteolytic dismantling of the cell represents the point of no return in programmed cell death. Moreover, cytosolic accumulation of CYCS feeds forward to permeabilize mitochondrial membranes further, enhancing release of proapoptotic factors in this death spiral. Curiously some evidence suggests that CYCS release by itself may not constitute an absolutistic executioner mechanism if cells can compensate for its loss from the electron transport chain. Nonetheless as the harbinger of caspase activation, CYCS remains integrally involved in intrinsic apoptosis central to development, homeostasis, and disease.


Human cytochrome C ELISA kit can measure concentrations of CYCS (cytochrome C, THC4, Cyt-C) present is plasma, serum, biological fluids or tissue homogenate samples.


All reagents supplied need to be stored at 2 °C – 8 °C, unopened reagents will retain reactivity until expiration date. Do not use reagents beyond this date.

  • One 96-Well Plate: Pre-coated with anti-CYCS antibody.
  • Standards: Lyophilized recombinant.
  • Sample/Standard Dilution Buffer.
  • Biotinylated-labelled Antibody.
  • Antibody Dilution Buffer.
  • HRP-Streptavidin Conjugate (SABC).
  • SABC Dilution Buffer.
  • TMB Substrate.
  • Wash Buffer (25x).
  • Plate Sealer.
  • Product Instructions.


For this cytochrome C ELISA kit, it is recommended that a standard curve is generated for each assay carried out.

Standard Curve: 0, 0.156, 0.312, 0.625, 1.25, 2.5, 5, 10 ng/ml.
Reactivity: Human
Sensitivity: 0.094 ng/ml
Range: 0.156 – 10 ng/ml
Principle: Sandwich, Double Antibody
Application: Research Use Only.


– Specificity: Highly specific for CYCS, no cross reactivity or interference between CYCS and analogues was detected.
– Recovery: Serum (85 – 103%), EDTA Plasma (89 – 105%), Heparin Plasma (90 – 104%).
– Linearity: Serum (90 – 104%), EDTA Plasma (83 – 99%), Heparin Plasma (87 – 99%).
– Precison Intra-Assay: CV < 8%
– Precison Inter-Assay: CV < 10%


  1. Cytochrome c: An extreme multifunctional protein with a key role in cell fate. Int J Biol Macromol. (2019) 136: 1237-1246. Santucci R., et al.
  2. CYCS gene variants associated with thrombocytopenia. Platelets. (2019) 30 (5): 672-674. Ledgerwood E.C., et al.
  3. A role of flavonoids in cytochrome c-cardiolipin interactions. Bioorg Med Chem. (2021) 33: 116043. Rice M., et al.
  4. Declined expressions of vast mitochondria-related genes represented by CYCS and transcription factor ESRRA in skeletal muscle aging. Bioengineered. (2021) 12 (1): 3485-3502. Kan J., et al.


Online Enquiry Form

"*" indicates required fields

Please check mark information required:


Your secretory IgA ELISA gave good results and I was also really impressed with how quickly we received it.

L. Johnston
PhD Student / University of Glasgow

It is refreshing to know that you have a technical team that is very knowledgeable. I have already recommended your company to other researchers in our department.

Dr. P. Anderson
Lecturer / University College London (UCL)

I am a first time user and found that your instruction manual was very easy to follow. The insulin ELISA assay performed well and I was happy with the results that were generated.

J. Thomas
Senior Technician / Addenbrooke’s Hospital

I carried out a pilot study comparing the performance of many ELISA assay's from different suppliers and found your kits to be one of the better performers. We observed good linearity and tight replicates.

Dr. C. Davies
Lead Scientists / AstraZeneca

You are my first point of contact when I am looking to purchase ELISA. You have such an easy and simple system, yet it is very effective.

A. Shaw
Purchasing / University of Oxford