Related Experiment Video
Updated: Aug 16, 2026
06:01
EPR Monitored Redox Titration of the Cofactors of Saccharomyces cerevisiae Nar1
Published on: November 26, 2014
Complex-formation between cytochrome c and cytochrome c peroxidase. Equilibrium and titration studies
The Biochemical Journal
|January 1, 1971
Summary
Yeast cytochrome c peroxidase forms complexes with cytochrome c, crucial for its catalytic activity. Studies reveal insights into enzyme-peroxide interactions and reaction mechanisms.
Area of Science:
- Biochemistry
- Enzymology
- Protein-protein interactions
Background:
- Cytochrome c peroxidase (CCP) plays a vital role in cellular redox processes.
- Understanding the interaction between CCP and its substrates, like cytochrome c, is key to elucidating catalytic mechanisms.
Purpose of the Study:
- To investigate the physical and chemical properties of complexes formed between yeast cytochrome c peroxidase and cytochrome c.
- To elucidate the catalytic mechanism of yeast CCP, particularly its interaction with cytochrome c and peroxide compounds.
Main Methods:
- Analytical ultracentrifugation
- Column chromatography
- Spectroscopic analysis
- Kinetic studies
Main Results:
- Complexes of yeast CCP with both ferricytochrome c and ferrocytochrome c were detected.
- Binding constants derived from chromatographic experiments align with kinetic data.
- The enzyme-peroxide intermediate exhibits differential reactivity with cytochrome c and ferrocyanide.
- Fluoride binding to CCP and its peroxide compound provides evidence for one-electron reduction pathways.
Conclusions:
- Complex formation is integral to the catalytic activity of yeast CCP towards ferrocytochrome c.
- The CCP-cytochrome c complex does not involve gross conformational changes in either protein.
- The mechanism of cytochrome c oxidation involves sequential reactions with enzyme-bound oxidizing equivalents.
Related Concept Videos
03:45Formation of Complex Ions
A type of Lewis acid-base chemistry involves the formation of a complex ion (or a coordination complex) comprising a central atom, typically a transition metal cation, surrounded by ions or molecules called ligands. These ligands can be neutral molecules like H2O or NH3, or ions such as CN− or OH−. Often, the ligands act as Lewis bases, donating a pair of electrons to the central atom. These types of Lewis acid-base reactions are examples of a broad subdiscipline called coordination...
01:43Electron Transport Chain: Complex III and IV
During the electron transport chain, electrons from NADH and FADH2 are first transferred to complexes I and II, respectively. These two complexes then transfer the electrons to ubiquinol, which carries them further to complex III. Complex III passes the electrons across the intermembrane space to Cyt c, which carries them further to complex IV. Complex IV donates electrons to oxygen and reduces it to water. As electrons pass through complexes I, III, and IV, the energy released aids the pumping...
01:23Complexation Equilibria: Overview
Complexation reactions take place when dative or coordinate covalent bonds form between metal ions and ligands. The compounds formed in these reactions are called coordination compounds. The number of bonds formed between the metal ion and the ligands is called its coordination number. Generally, most metal ions in an aqueous solution are solvated by water molecules and thus exist as aqua complexes.
The equilibrium constant of the complexation reaction is represented as the formation constant...
The equilibrium constant of the complexation reaction is represented as the formation constant...
00:39Complexometric Titration: Overview
Complexometric titration involves the formation of a complex by reacting a metal ion with one or more ligands. A visual indicator often detects the end point of a complexometric titration. It is added to the metal solution before the titration, forming a stable metal–indicator complex and imparting color to the solution. As the titration approaches the equivalence point, the excess of the added ligand displaces the indicator from the metal–indicator complex, releasing the free indicator. The...
01:09EDTA: Conditional Formation Constant
Each EDTA molecule has six binding sites: four carboxyl groups and two amino groups. The fully protonated form of EDTA is represented as H6Y2+. However, it can exist in different forms, H5Y+, H4Y, H3Y−, H2Y2−, and HY3−, depending on the pH of the solution. In very basic solutions with pH > 10.17, the fully deprotonated form, Y4−, is the predominant species that readily complexes with metal ions in a 1:1 ratio.
For the equilibrium reaction of the metal with the Y4− form of EDTA, the formation...
For the equilibrium reaction of the metal with the Y4− form of EDTA, the formation...
01:26EDTA: Auxiliary Complexing Reagents
EDTA titrations are usually carried out in highly basic conditions, where the fully deprotonated form of EDTA, Y4−, actively complexes with the free metal ions in the solution. Several metal ions precipitate as hydrous oxide (hydroxides, oxides, or oxyhydroxides) under these conditions, lowering the concentration of free metal ions in the solution. For this reason, auxiliary complexing agents or ligands such as ammonia, tartrate, citrate, or triethanolamine are used in EDTA titrations to...