We often are so involved in our local, may be important, but still local, that behind a few trees we do not see the Forest.
Hydrogen is the most common element in the Universe. Hydrogen is burned in the stars/ Some of them explode and produce other elements, which are necessary for the Life. Most importantly oxygen, which reacts with the hydrogen in the universe and produces water. So, Space is full of water, but not of oxygen. Nuclear reactions in our Sun produce much energy, including Light, which was and still is used by plants to split water into O and 2H. From hydrogen and CO2 carbohydrates are made and so on. It is simplification, of course. What I am puzzled with, is that plants appeared on Earth 1.5 billion years later than mitochondria! Besides, as a mitochondriologist, I wander how to comprehend the roles of hydrogen (H) and protons (H+) when they are almost one and the same.
It is just a little philosophical game for the brain to ask "stupid" questions.
Who wants to play?
Congratulations you have successfully started your first discussion. It will take me some time for me to read your paper and comment on it. It’s not really my area of expertise. But that never stopped me before.
Yiguo Zhang
What are you referring to when you say: "it is also a toxic when over-produced."?
H2 production via Steam Methane Reforming is actually a realtively clean process.
Dear Rick, thank you for joining the discussions.
Unfortunately, I have deleted the previous discussion and cannot recall to what "toxic when over-produced" is related.
In the last few years so many discoveries have been made that one needs the time and someone else to comprehend and discuss the issues. One of the discoveries are molecular machines, than how plants appeared on Earth. It is an important question because the burst of evolution has begun only after the planet had plants. It is not the oxygen, but the amount of food that plants produce for other species. Food is the source of hydrogen for others. Still, why there are no animals with efficiency of plants? Or they will appear in the future. Finally, I think that everything in the Space and on Earth is so thoughtfully designed. My materialism, which I was taught in the USSR, is shaken. Finally, just few days ago I learned that in mitochondria the temperature is about 50oC, and that free radicals are not responsible for mutations of mtDNA. Hydrogen has relation to all these issues because it is the source of energy. I think that formation of perhydroxyl radical from superoxide and protons is a key event for understanding oxidative stress and aging.
@Yiguo Zhang Added a reply to the previous discussion it said: it is also a toxic when over-produced.… Apparently referring to H2
Alexander V Panov Thanks for opening a new discussion.
My major background is kinetics, chemistry of free radicals, and homogeneous catalysis of redox processes. It happened that I have developed a simple antioxidant assay and currently working on artificial photosynthesis (water splitting).
Before to start a discussion let's define key terms.
Hydrogen (often called dihydrogen) is the H2 molecule.
H is the hydrogen atom,
H+ is the proton.
Oxygen or dioxygen is O2 molecule in a ground state.
O is an oxygen atom.
Quick comments:
In photosynthesis light does not to split water into O and 2H.
Hydrogen is NOT burned in the stars. " Combustion is a chemical reaction that occurs between a fuel and an oxidizing agent that produces energy, usually in the form of heat and light. ... It is also known as burning. " (https://www.thoughtco.com/definition-of-combustion-605841)
"the roles of hydrogen (H) and protons (H+) when they are almost one and the same. " Hydrogen (H) and protons (H+) are two completely different chemical entity.
What is the "Biology of Life?" Biology is the study of living organisms. "Bio" means "related to life."
"plants appeared on Earth 1.5 billion years later than mitochondria!" Interesting, never heard before. A probable answer is the "Anaerobic respiration" which uses electron acceptors other than molecular oxygen.
http://www.hcs.harvard.edu/ethiohs/constitution.php
I haven't really read it but based on a quick 5 minute skim I think it basically says you don't actually know how long ago and of these things really happened because your assumptions may be wrong.
Personally I would be shocked if anybody's assumptions about what took place 1.5 billion years ago can be proven to be true.
"Hydrogen (H) and protons (H+) are almost the same." Well, the difference is in one electron. But this electron plays a fundamental role in biochemical transformations. Regards,
In addition, the formation of H+ from water in carbohydrates biosynthesis is a very complicated process involving, among others, NADP+ and ADP. Regards,
Welcome! My dear colleagues to the discussion. Of course, "Hydrogen" as such is just a pretext from previous discussion of someones question. And, of course, stars do not "burn" hydrogen.
It is nice that Yurii is a Chemist. There are many things I would like to discuss. But I apologize, if I will not answer sometimes quickly. I have a little grandson (4 months) and another highly active one (3 years). Therefore our kids need help.
When I wrote about the sameness of H and H+, I kept in mind that in mitochondria their interactions are very tricky. For example, H+ is at the same time an acid and a cation.
I fully appreciate the Miroslaw's comment that the "simple" work of the first photosynthetic organisms was in reality very complicated. Together with the discovery of molecular machines that raises "funny" questions about evolution.
I won't complltely rule out the possibility that some star somewhere in the universe might contain both H2 and O2 and they might burn there but I agree that's not normally what happens on the stars that we know about.
Alexander V Panov, The problem is that you use shortcuts and simplifications. Hence some misunderstandings But the discussion you started seems to be interesting. Regards,
This discussion was inspired by the question raised in another thread : "Hydrogen is Homeostasis regulator. " As I've already written, for chemists the hydrogen is the H2 molecule. I don't believe that H2 is involved in the processes in living organisms. Proton is never called "hydrogen." Proton is a key player in redox reactions. A good example is the Proton Coupled Electron Transfer, PCET, reactions. As far as I understand, Alexander V Panov defines all 1-electron donors as "H," which is extremely confusing. The atom of hydrogen is very reactive and its formation is very unlikely in vivo.
I am not really sure what the topic of this discussion is. I think so far there is a provocative implication that H2 or maybe H had a prominant role in the development of life in the universe and the well reasoned assumption that plants appear long before animals and a statement that mitochondria the temperature is about 50oC, and that "free radicals are not responsible for mutations of mtDNA. Hydrogen has relation to all these issues because it is the source of energy. I think that formation of perhydroxyl radical from superoxide and protons is a key event for understanding oxidative stress and aging." Where do we go from here?
Rick Manner "Hydrogen has relation to all these issues because it is the source of energy. " H2 is chemically very inert molecule. As far as I know there is no enzymatic system to use H2 as a source of energy. H2 is not produced by photosynthesis. H2 has a very low solubility in water and easily escapes from solutions. I don't believe that H2 is an important in vivo.
" I think that formation of perhydroxyl radical from superoxide and protons is a key event for understanding oxidative stress and aging." This question has been thorough discussed in the literature. The reactivity of HO2(.) and O2(-.) are
well studied. The problem is in the low pKa value of perhydroxyl value, pKa ~ 4.8. Therefore, under physiological conditions (pH 7.4 of our blood), HO2(.) is fully deprotonated.
Alexander V Panov PLZ, clearly formulate for the beginning a single question for further discussion.
I fully agree with what Yurii V GEletii had mentioned. H2 is there in plenty in universe and also on Jupiter and Saturn(?) but not even in trace amount in this planet and hence H2 is not an important one. H2 and O2 have little or no solubility at all.
I think it is enough about hydrogen. What could be the subject for discussions and communications in such a distinguished
I am not sure myself what we discuss here. Of course H is not "burned" in Stars and H2 as a gas has nothing to do with mitochondria, but again it is used in combustion engines and again with oxygen. When I was working on my book Functional Bioenergetics (in Russian) I found many interesting facts regarding evolution of Life on Earth, including the fact that the burst of has begun only after plants appeared on the planet. I was shocked that it happened more than a billion years after the cells with mitochondria.
Yurii, I do not consider as "H" any other one electron donors. But I do not agree that H and H+ are too distinct. In one paper on the mechanism of proton transport in water, through the Grotthus mechanism with formation of the Zundel's and Eigen's ions, it was mentioned that this very mechanism plays a role in the redox reactions in some enzymes. Just add an electron to H+ and you get H added to a compound (reduced).
I think it is enough about hydrogen. What could be the subject for discussions and communications in such a distinguished company of researchers.
Risk, what are you interests? To Yurii, as a chemist, I have a question. You have mentioned that one of your interests is the kinetics of chemical reactions. So here is the question #1: if indeed inside mitochondria the temperature (T) if 50C, how it might affect the state of the membrane and biochemical reactions? I think that this T is extremely local but numerous (like hot spots). I have more questions to discuss.
Happy weekend to everybody!
We could have a more conventional discussion about H2. For example:
H2 is primarily produced as a byproduct of gasoline octane improvement (Naphtha-Reforming) and olefin production (mostly ethylene/propylene) and on purpose via steam methane reforming (CH4+H20 CO + 3 H2 followed by CO+H2O H2 + CO2. On propose SMR varies from 50-70% energy efficiency. Is this a good deal? Should we convert CH4 into H2 to produce a clean fuel or are there better ways to reduce ghg emissions?. Some even produce using electrolysis to produce H2 – is this ever the correct solution?
Thank you Rick for your valuable comment. Interestingly, researches working on fuel efficiency, use perhydroxyl radical (J2) to increase combustion. HO2 has extremely high affinity for allylic hydrogen of polyunsaturated fatty acids. Interesting, could it react with H2 at high temperatures in the engine.
And I have recalled, as an aswer to Yurii, to his objection that H and H+ are similar. As a matter of fact, when dehydrogenases reduce NAD+ or NADP+, One hydrogen is attached to NAD(P)+ --> NAD(P)H and another hydrogen exists as H+: NAD(P)H + H+.
Alexander V Panov " But I do not agree that H and H+ are too distinct." You may disagree but must prove your statement. " Just add an electron to H+ and you get H added to a compound (reduced)" Easy to say but difficult to do. " HO2 has extremely high affinity for allylic hydrogen of polyunsaturated fatty acids " Define what is the "affinity." "could it react with H2 at high temperatures in the engine." In what engine, the internal combustion? The reaction of O2 with H2 is very well studied, the mechanism includes more than 200 reactions.
I doubt but can't rule out that the temperature in mitochondria could reach up to 50C. Biochemical reactions are the same as chemical reactions and commonly are faster with an increase of temperature.
"As a matter of fact, when dehydrogenases reduce NAD+ or NADP+, One hydrogen is attached to NAD(P)+ --> NAD(P)H and another hydrogen exists as H+: NAD(P)H + H+. " This is a typical Proton Coupled Electron Transfer (PCET) processes. Well studied, nothing exceptional. Has nothing to do with similarity between H and H+
Rick Manner "Should we convert CH4 into H2 to produce a clean fuel or are there better ways to reduce ghg emissions?. Some even produce using electrolysis to produce H2 – is this ever the correct solution?" The storage of H2 is the main problem. It's simpler to use CH4 directly as a fuel. Water electrolysis to produce H2 is actually the splitting of water to H2 and O2. The cost of electrical energy determines the price tag of H2. When the price of renewable energy becomes low, the electrolysis could be profitable (providing the problem of H2 storage is solved)
More and more interesting. The difference in one electron, as I wrote at the beginning of the discussion, is a very big difference. When it comes to the storage of hydrogen, indirectly methanol and DME are used - and then CO2 is also "stored" for some time. Regards,
Miroslaw, Yes reactively H2 and CH3OH are actually very similar compounds. "Storing" H2 as CH3OH before transporting i across the ocean and converting it back into syngas/H2 is a very good way to transport H2- much better than refrigerated vessels.
When you talking about fuels (e.g. for cars), the most important parameter is the energy density. The standard unit for energy density is megajoules per kilogram (MJ/kg). The energy density for methanol is around 22 MJ/kg. Hydrogen has one of the highest energy density values per mass. Its energy density is between 120 and 142 MJ/kg. For a practical use the energy density is expressed in Mj/L.
For Hydrogen (compressed at 700 bar) 9.17Mj/L, for methanol 19.7 Mj/L, LPG (including Propane / Butane) ~ 46. Thus, the problem is to convert H2 to a liquid fuel.
Thank you for the interesting information/ How I would know this without communicating with people from other fields. What large "M" means "Mega" or "Milli"? and how to pronounce these values?
Miroslaw, Producing and shipping DME instead of Methanol would also be a reasonable way way to thrasport natural gas equivalent to China. But I think the Chinese have chosen to primarily ship metahanol instead.
Rick, DME as "natural gas equivalent"? I did not meet with this term. Sounds interesting. For me, DME is primarily an alternative, a clean-burning, non-toxic, potentially renewable fuel for diesel engines and as well as refrigerant. Regards,
Methanol and DME have the similar energy density ~20Mj/L. DME is currently considered is an alternative fuel for diesel engines. Like LPG, DME is gaseous at normal temperature and pressure, but changes to a liquid when subjected to modest pressure
There is nothing wrong with chosing DME instead of methanol as a way avoid transporting LNG - except te Chinese appear to have chosen to focus on methanol instead of DME and have converted engines to burn methanol If there was a shortage of methanol but large amounts of DME was still available I suspect the Chinese would buy it.
Yurii, Thanks for giving the value of DME enegy density. I wonder, if a slight difference to methanol results from a similar mass fraction of hydrogen in both chemical compounds. Regards,
Methanol can be easily converted to DME which can be converted to olefins or gasoline via the ExxonMobil MTG process using ZSM-5 catalyst if desired. The Chinese have instead chosen to modify engines so they can burn methanol directly in many of their vehicles.
Well, Not only can methanol be dehydrated to DME in the presence of zeolite catalysts, e.g. HZSM-5, but also DME can be directly obtained from synthesis gas using bifunctional catalysts. We deal with the kinetics of methanol and DME synthesis in the IChE PAS for many years. Regards,
"What I am puzzled with, is that plants appeared on Earth 1.5 billion years later than mitochondria!"
Strictly speaking, photosynthetic water oxidation could have originated closer to the origin of life . A recent work by Oliver et al. (Oliver, T.; Sánchez-Baracaldo, P.; Larkum, A. W.; Rutherford, A. W.; Cardona, T. Time-Resolved Comparative Molecular Evolution of Oxygenic Photosynthesis. Biochim. Biophys. Acta Bioenerg. 2021, 1862 (6), 148400. https://doi.org/10.1016/j.bbabio.2021.148400.) found CP47, CP43 -- core proteins in photosystem II responsible for providing driving force behind ATP synthesis, diverged at about the same time as F-type ATP synthases, about 4 billion years ago.
Dear Doris, you are completely right. The photosynthesis itself appeared at the very dawn of Life on Earth. But it was not as productive as it goes on in plants. The point is, that having both mitochondria and chloroplast made plants productive enough to provide foods for the burst of evolution.
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