Do you often feel exhausted, even after a full night’s sleep, and struggle to find energy? Do you long for more sustained energy to face life’s challenges? If your answer is yes, PQQ pyrroloquinoline quineone might be the “energy key” you’ve been searching for.
PQQ, short for Pyrroloquinoline Quinone, is a remarkable substance found in nature. Although not as widely known as vitamins, it plays a crucial role in cellular energy metabolism.
Introduction to PQQ
PQQ, scientifically known as 4,5-dihydro-4,5-dioxo-1-hydro-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylic acid, is also known as Pyrroloquinoline Quinone (PQQ). It is produced by Gram-negative bacteria and has a broad nutritional effect on microorganisms, plants, and animals, along with antioxidant properties.
Discovery History of PQQ
The first research on PQQ can be traced back to 1959 when scientists studying glucose metabolism in non-phosphorylated bacteria (which metabolize glucose through the glucose-6-phosphate pathway) discovered that Acinetobacter calcoaceticus contained a glucose dehydrogenase (GDH) enzyme that did not depend on NAD(P) and FAD. Subsequently, Haug isolated a cofactor from this enzyme that had a maximum absorption spectrum at 248nm, with steps at 270–280nm, and suggested this cofactor might be a derivative of naphthoquinone.
Around the same time, researchers became interested in single-cell proteins and biopolysaccharides and began studying the process by which certain bacteria metabolize methanol. They found that some bacteria, such as Pseudomonas sp. M27, could grow on media with methanol or methane as the only carbon source. The key enzyme for this process, methanol dehydrogenase (MDH), also yielded an organic cofactor, which was not NAD(P) nor FAD.
In the late 1970s, Duine and colleagues used techniques such as electron spin resonance (ESR), NMR, and MS to re-study the structure of MDH. In 1979, they proposed that the cofactor was a quinone structure containing two nitrogen atoms. Around the same time, Salisbury and others used X-ray crystallography to analyze the acetone adduct of this cofactor, confirming it as a tricarboxylic pyrroloquinoline quinone structure with the formula 4,5-dihydro-4,5-dioxo-1-hydro-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylic acid.
The discovery of PQQ marked a significant event in the history of quinone enzyme research. It not only introduced a new cofactor but also indicated the emergence of a new branch of enzymology, namely quinone enzymes, which are enzymes that use PQQ and other quinone compounds as cofactors. Before the discovery of PQQ, it was believed that oxidoreductase enzymes only had NAD/NADP and FAD/FM as cofactors.
Sources of PQQ
PQQ in nature is primarily synthesized by Gram-negative bacteria (G-). Through natural material cycles, it affects animals, plants, and other microorganisms outside of G- bacteria.
| G-bacteria that produce PQQ | Acinetobacter calcoaceticus |
| Klebsiella pneumoniae | |
| Pseudomonas fluorescens | |
| Methylobacterium extorquens | |
| Methylobacterium organophilum | |
| Gluconobacter oxydans | |
| Enterobacter intermedium | |
| Deinococuus radiodurans | |
| Erwinia herbicola | |
| Methylobacteriu flagellatum | |
| Pseudomonas aeruginosa |
PQQ’s strength lies in its ability to:
- Activate Mitochondria and Boost Cellular Energy: Mitochondria are known as the “energy factories” of cells, and PQQ acts like an efficient “factory manager” by stimulating mitochondrial generation and repair. This enhances cellular energy levels, helping you bid farewell to fatigue and feel revitalized.
- Act as an Antioxidant and Slow Aging: PQQ is a powerful antioxidant that effectively removes free radicals in the body, protecting cells from oxidative damage, thus delaying aging and maintaining youthful vitality.
- Protect Neurons and Enhance Cognitive Function: PQQ can cross the blood-brain barrier and directly act on the brain, protecting nerve cells and improving memory, learning ability, and cognitive function.
- Promote Heart Health: PQQ improves heart function and reduces the risk of heart disease.
Foods Containing PQQ
Although PQQ can be found in a variety of foods such as fermented soybeans, green peppers, kiwi, and parsley, the levels of PQQ in a typical diet are often relatively low. Therefore, to ensure adequate intake, considering PQQ dietary supplements might be beneficial.
PQQ content of various foods | |||
| Food Name | Content(ng/g or ng/ml) | Food Name | Content(ng/g or ng/ml) |
| Broad bean | 17.8 | Green tea | 29.6 |
| Kiwi fruit | 27.4 | Parsley | 34.2 |
| Soybean | 9.3 | Oolong tea | 27.7 |
| Citrus | 6.83 | cabbage | 16.3 |
| Potatoes | 16.6 | Carrot | 16.8 |
| Papaya | 26.7 | spinach | 21.9 |
| Sweet potato | 13.3 | Tomato | 9.2 |
| Celery | 6.3 | Apple | 6.1 |
| Green pepper | 28.2 | Banana | 12.6 |
| Fermented soybean (Natto) | 61.0 | Doufu | 24.4 |
Gram-negative bacteria synthesize PQQ through seven genes, named pqqA–G. These genes express and divide the following tasks:
| PQQ synthetic gene | Feature |
| pqqA | Provides precursors for PQQ biosynthesis |
| pqqB | The existing transporters were modified to transfer PQQ from the plasma membrane to the cytoplasm |
| pqqC | Enzymes that catalyze the last step in the PQQ synthesis reaction |
| pqqD | Necessary enzyme whose function is not yet clear |
| pqqE | Cofactor of PQQ synthesis reaction |
| pqqF | After the current body completes the loop, it is cut off from the pqqA precursor |
| pqqG | After the current body completes the loop, it is cut off from the pqqA precursor |
Currently, it is known that the raw materials for PQQ synthesis are tyrosine and glutamate, with the final step of synthesis shown below:
