Post n.28 English
The amino acids, that make up proteins exist in two forms, Destro and Levo, a mirror image of the other, as we have amply exposed in the articles regarding the molecular asymmetry problem. These two molecular forms have the same chemical-physical properties and therefore always appear together. Since both the D-form that the L-form, in the prebiotic era, were surely dissolved in water, the molecular disorder would produce cross reactions between L and D amino acids and give rise to proteins containing the two forms, but of no biological interest. Now the issue is that all the proteins in all living organisms are made up only of the L-shaped amino acids. Life is so asymmetrical, how did this choice occur? For more than a century and a half the researches were often oriented towards existence, in the mineral world, of an asymmetric material that conditioned the choice. Starting from the Bernal theory on the role of clays and quartz, polarimetric observations (post n. 22) have put in evidence how the colloidal silica rotates the plane of polarized light to the left. The colloidal silica may be that asymmetrical mineral much sought throughout time, which favored the L-amino acids. We have assumed that the deviation of the polarized light of the colloidal silica is due to the formation of helical structures of Levo quartz type. If the colloidal silica in aqueous solution gives rise to helical structures, they are as likely to form structures that both Destro & Levo structures.
Why did the Levo prevail?
In the article "The Origin of proteins: the molecular asymmetry problem (fifth part)" had suggested that the Earth's magnetic field had played a vital role in the asymmetry of the colloidal silica. In fact, the article concluded: «Ultimately the tetrahedral structural units of the silica, when binding to form colloidal particles they could have any orientation and even the slightest external contribution may have given a preferred direction. This contribution could be given to the combined effect of the Earth's magnetic field and the three factors listed below: the asymmetry of water, the formation of clusters and the tetrahedral structural unit.
It is possible that this combined effects impose a preferred direction and the cause of the asymmetry of the colloidal silica».
So then, eliminating the Earth's magnetic field, the asymmetry of the colloidal silica should disappear.
My relationship with Magistri Cumacini, the High School where I taught for almost thirty years, is still ongoing. A group of teachers, now retired, work at the reordering and cataloguing operations of the school library.
The question on the magnetic field, in reality, was not posed by me, but a dear colleague, Physics Professor Clemente Cattaneo. In fact, as Clemente explained to me, Earth's magnetic field can not be eliminated completely but anyway we decided to try.
The kindness and the interest of the Engineer, Enrico Tedoldi, Headmaster, who granted us permission, was ever present.
After measuring the magnetic field in the laboratory, corresponding to 0.16 Gauss, Clemente prepared the necessary equipment. This is consisted in a 20 cm of 150 solenoid coils, traversed by a continuous current of 17mA which generates a magnetic field of approximately 0.16 Gauss. By placing an inversed field compared to Earth’s, we definitely reduced if not canceled out the field in the area. Unfortunately we could not assess the variation of the field produced by the metal parts of the polarimeter, but we are certain that the influence is negligible compared to the field created by the solenoid. We found that a sensitive compass did not undergo significant deviations within the polarimeter which is made up of pervalently aluminum, stainless steel and plastic.
With a direct polarity the field was, however, increased.
For the experiment were used Na2SiO3 (soluble glass) in H2O and CH3CH2OH (ethyl alcohol), magnetic stirrer, polarimeter "Polax 2L".
In Polarimeter the metal staff of the test tube was replaced by an identical wooden support.
Procedures and data:
1) Standard procedure:
0.3g Na2SiO3 in beaker, added 38cc of H2O on a magnetic stirrer at 300 rpm for 1 minute.
Added 12cc of CH3CH2OH and continue the agitation for half a minute.
Take off beaker from the agitator and let sit 2 minutes.
After sitting, the solution is poured into the polarimeter tube, it is closed and sits on the support inside the polarimeter; time required 1 minute.
Let the solution sit from 1 to 2 minutes in the polarimeter and then the measurement is taken.
2) Procedure to decrease the magnetic field of the circuit:
Perform the standard procedure but the circuit is placed outside of the polarimeter tube before filling it.
Deviation of the plane of polarized light: -0.20
Deviation of the plane of polarized light: First test: -0.15; Second test: -0.20
We do not know how much the circuit lowers the Earth's magnetic field. One can conclude however, that no decrease in the deviation of the polarized light which goes beyond the limit of sensitivity of the polarimeter is observed.
If the magnetic field contributes to the asymmetry of the colloidal silica, by increasing the magnetic field, the deviation of the polarized light must increase.
This question was asked once more by Clemente.
Here we played on reliable data: placed the solution under four times the Earth's magnetic field. As it often happens in researches the unexpected occurs: The deviation of the polarized light wasn’t increased, but had disappeared. The colloidal silica lost its asymmetry.
1) Standard procedure: as above
2) Standard procedure , 4 times the Earth's magnetic field, entering the external circuit of the polarimeter tube before filling.
Deviation of the polarized light (the tests were carried out alternately).
Procedure 1) First test: -0.25, Second Test: -0.20, Test Three: -0.20
Procedure 2), First Test: 0, Second Test: 0, Round Three: 0
In order to draw definitive conclusions of the magnetic field at different values, a number of tests should be done and a graph plotted. I, however don’t have more than one laboratory, and it is not correct to abuse of the kindness of others. The tests described above are therefore a clue, a strong indication of the role played by Earth's magnetic field.
It is possible that without the presence of a magnetic field there may be no asymmetry of the colloidal silica. The appearance of a magnetic field imposes, through the tetrahedrons of water, a slight rotation on the siliceous structures, and therefore the appearance of the asymmetry of the colloidal silica. It is likely then that beyond a certain value, Earth's magnetic strong magnetic field does not induce a rotation, but imposes a strong alignment of the small magnetic fields of water molecules destroying the asymmetry of the colloidal silica.
To make precise polarimeter measurements the following instructions are necessary.
In use, the polarimeter heats up after some time from 20 ° C to 26 °- 27 ° C.
By varying the temperature of the polarimeter also the zero of the polarimeter varies. By working at room temperature, turning on and off the polarimeter doesn’t keep it at a constant temperature and therefore we must constantly chase the zero. It is best to turn the polarimeter on, wait on average 2 hours until the temperature stabilizes and then reset for the zero. Check the temperature at each reading, the oscillations must not be greater than ± 0.2 ° C.
The screw cap and the slide of the polarimeter tube must always be in the same position and to avoid errors due to the thickness of the glass or the inner rubber seal. Make marks on the slide and on the capsule and place it always at the same position.
If during closing the glass does not stay attached to the rubber gasket, put a droplet of water on the seal and place the glass on top.
When the polarimeter is reset in a void, if you insert the polarimeter tube with water different values can be observed if it is rotated. Glue a sticker with four signs on the polarimetric tube. Observe the polarimeter, rotate it in the four positions and choose the position with results closest to zero. Reset it and start to measure the sample using that as a reference point.
Translated by: Sydney Isae Lukee