Metal ions in proteins and other organic substances

Many proteins in body use metals for many reasons from molecule transport to chemical reactions and fetal development. Due to their electronegativity metals mixed with water get around +1 or +2 charge that makes them some of the most positively charged elements in body.

Above structure describes one chelation agent EDTA that is used to bind with metals including calcium and remove them from body (overuse of chelation agents can kill due to low calcium). Proteins that have metals have often similar regions with 4-6 nitrogen or oxygen atoms creating negatively charged zone for metal ion.

One of the most common structure that body uses is porphyrin structure shown above. It could contain different metals and participate in very different roles. For example in hemoglobin this structure surrounds iron and in chlorophyll it surrounds magnesium. If bound with iron this group gets called heme.

Iron containing proteins can carry oxygen without reacting with them chemically. Cytoglobin may be most common as it is present in most tissues. Hemoglobin is mainly in blood, myoglobin in muscles and neuroglobin in neurons. Having more of those proteins tends to make tissues more resistant to lack of oxygen. They seem to have somewhat fluid way of transporting oxygen by temporarily binding and releasing them often but most likely attraction is towards heme group that doesn't have same charged oxygen already there so they tend to even out oxygen levels through body (free dissolved oxygen can easily go through cell walls unlike globin proteins). 
At least myoglobin seems to be produced more in case of low oxygen levels like during exercise. This seems to also apply on hemoglobin. That's probably reason why living in high altitude or exhausting bodies oxygen stores with activity cause additional hemoglobin and myoglobin so body could store more oxygen. Increase in calcium release seemed to be that maybe main signal substance for muscles that also increases their production. Superficial search (1, 2) of "calcium" and "muscle growth" seemed to show that blocking calcium also block growth and division of muscle cell and that it is involved in growth of muscles starting from fetal development and extra activity of calcium due to extra muscle activity increase growth of muscle cells.

Another substance that uses porphyrin + iron is catalase that converts hydrogen peroxide to water and oxygen with 4 such structures in each catalase molecule turning millions of peroxide molecules to water and oxygen each second making it one of the fastest working protein. It's speed makes sense if considering electric charges. Oxygen is most negatively charged part in this cycle and all elements in porphyrin are relatively positive compared to oxygen. 
Events that cause it to break could go something like this: In HOOH structure H are more positive atoms and middle oxygen atoms stay negatively charged. In center of catalase is iron with probably +2 charge and it's surrounded by somewhat negatively charged nitrogen. This makes oxygens attracted to metal and hydrogen atoms to nitrogen or carbon groups around metal probably accelerating all atoms involved towards each other. If they get close enough metal becomes most likely source of electrons to oxygen and stronger temporary connections form between iron and oxygen. If free electrons of O are used to connect with Fe then oxygen atoms likely loses electrons that used to connect it with other oxygen atom and also while getting electrons from metals, oxygens will not have connecting electrons but will have similar negative charges that further push them apart.  

Some proteins that break up proteins also need metals. For example metalloproteases need at least zinc and if EDTA removes metals then these proteins can't break other proteins by possibly similar to catalase mechanism of offering easy electron source that disrupts the usual flow of electrons that keeps molecules together.

Maybe voltage differences between metals and oxygen or nitrogen is strong enough that when proteins force other molecules against this unusual (for body) voltage difference breaks them up.

Probably largest voltage difference between atoms in reactive proteins/enzymes is the part where metal is held. This could make it most likely place to send out more energetic electrons as this place has elements with largest difference in electronegativity. In chlorophyll it seems like likely place for getting free electrons.

Structure of chlorophyll c1. Light photons are polarized in some direction which could also push or pull electrons along this polarization direction. If electrons are already close to moving in some direction then electromagnetic radiation of light can add further push in that direction. Chlorophyll needs water molecules which attract oxygen and its hydrogen atoms may be attracted to negatively charged nitrogen atoms somewhat similar to catalase protein but in case of chlorophyll light is also needed to start chemical reaction. Maybe porphyrin with water creating electron flow could be useful for solar energy.

Chlorophyll molecules are in PSII and PSI and they are not the only ones there (each with around 100 molecules or elements including iron and other charged ions). It seems like 1 chlorophyll molecule can turn 1 photon into 1 electron plus this process break up water into oxygen and free protons which in turn are both used to produce energy by plants and animals. These free hydrogen ions produce ATP by ATP synthases and even there electrostatic interactions seem to help explain ATP synthesis. It usually takes around 3 H+ flowing through ATP synthase to produce 1 ATP from ADP by adding extra phosphate groups.

Phosphate groups usually have negative charges unless they get neutralized with 3 hydrogen atoms. ATP has energy because its 3 phosphate groups in row have strong repelling force pushing away from each other but in ATP synthase they manage to get close enough for connecting. It could possibly happen because ADP gets in, hydrogen ions neutralize one of the phosphate groups so they would not try to repel. Possible that added hydrogen on phosphate is attracted to some still charged phosphate with such strength that it bounces of -OH from one phosphate which could grab some free H+ to become water and connect 3rd phosphate group to ADP turning it to ATP.