1 / 13

Nitrite Reductases

Different Types of Nitrite Reductases. 3 Periplasmic ReductasesCytochrome c Respiratory Nitrite ReductaseCytochrome cd1 Nitrite ReductaseCopper Nitrite Reductase1 Cytoplasmic ReductaseNADH-dependent Siroheme Nitrite Reductase. Two types of Heme's in Cytochrome cd1. Cytochrome c . Cytochrome d1

quintana
Download Presentation

Nitrite Reductases

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. Nitrite Reductases A foray into the many types, functions, and intermediates of Nitrite Reductases

    2. Different Types of Nitrite Reductases 3 Periplasmic Reductases Cytochrome c Respiratory Nitrite Reductase Cytochrome cd1 Nitrite Reductase Copper Nitrite Reductase 1 Cytoplasmic Reductase NADH-dependent Siroheme Nitrite Reductase

    3. Two types of Heme’s in Cytochrome cd1 Cytochrome c Cytochrome d1

    4. Cytochrome cd1 Found in Paracoccus and Pseudomonas Heterodimer Each monomer composed of two domains Cyt c covalently bound to smaller domain Cyt d1 noncovalently bound to 8 bladed ß-propeller

    6. Cytochrome cd1 Reduces NO2- ? NO

    7. Copper Nitrite Reductase Found in Pseudomonas Homotrimer Each monomer forms two ß barrel domains Each enzyme contains six Copper Centers 3 Type I 3 Type II

    8. Copper Nitrite Reductase Electrons donated from donor proteins to Type I center Electrons come from cupredoxins and cytochromes Type I center donates electrons to Type II center Type II center = site of catalytic activity

    9. Copper Nitrite Reductase Uses a Copper (I) cation bound to the enzyme to bind NO2- Produces nitric oxide (NO) in the presence of Nitrite ions (NO2-)

    10. Copper Nitrite Reductase However, in the presence of both Nitric Oxide (NO) and of Nitrite ions (NO2-), the enzyme further reduces nitrogen to Nitrous Oxide (N2O).

    11. Less Useful Reductases Cytochrome c Respiratory Reductase Does not contribute to denitrification Overall Reaction: NO2- ? NH3 NO2- ? NO+ ? NOH ? NH2OH ? NH3

    12. Less Useful Reductases NADH-Dependent Siroheme Nitrite Reductase Unlike the other three, this one is found in the cytoplasm Most likely serves to remove NO2- from the cell (toxic at high levels) NO2- ? NH4+

More Related