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Biomedical subjects

C Portelli

Publications and source records attributed to C Portelli.

32 records · Page 2Linked to original sources
PubMedDate not supplied

Symmetrical-asymmetrical codons and hydrophobic-hydrophilic amino acids.

The symmetrical codons present in the first and third positions two purine (P) or two pyrimidine (p) bases (e.g. PNP or pNp), while the asymmetrical codons present in the first and third positions a purine and a pyrimidine base (e.g. PNp or pNP). The percentages of symmetrical and asymmetrical codons specifying hydrophobic and hydrophilic amino acids are similar in the genes of viruses and vertebrates, which utilise the "universal" genetic code, but they are different for the genes of human mitochondria and yeast mitochondria, which utilize two specific genetic codes.

Amino Acids↗
PubMedDate not supplied

The distribution of codons by classes of triplets in the sequence of genes.

According to a criterion of symmetry-asymmetry, the triplets of the genetic code can be divided into four classes. In the genes of viruses and human mitochondria, the frequency by which a codon is followed by a codon of the same class is higher than that theoretically estimated. This is the consequence of the fact that in an initial stage of evolution many codons were duplicated.

Base Sequence↗
PubMedDate not supplied

The biomolecular mechanisms of motion and the role of the electroweak force.

The biomolecular mechanisms of motion present certain specific asymmetrics. For instance, the head of myosin makes a rotation in the clockwise sense to achieve a connection with an actin-G molecule. The symmetrical in mirror correspondent of this asymmetry could only arise in a biological world formed by antimatter (symmetry CP). This fact indicates that the electroweak force interferes in the biomolecular mechanisms of motion.

Animals↗
PubMedDate not supplied

The symmetries of the genetic code of mammalian mitochondria.

The genetic code of mammalian mitochondria presents some symmetric in the sequences of certain codons and in the relationships existing between the codons and aminoacids. These symmetries suggest the classification of codons in four classes and indicate that the evolution of the genetic code developed in four stages.

Amino Acids↗
PubMedDate not supplied

The role of the sodium, potassium, magnesium and calcium ions in the transfer of bioenergy, and the possibility of their substitution by other cations.

According to a previously presented model, two sodium ions and one calcium ion form an electric polarizing system of the diverging type, which favours the breaking of the high-energy bond of the ATP molecule, while two potassium ions and one magnesium ion form an electric polarizing system of the converging type, which helps the rebuilding of the high-energy bond of the ATP molecule. The condition required by one of the above-mentioned ions to be replaced with another type of ion (belonging to the same subgroup in Mendeleev's Table) capable of having a similar physiologic function is that the substitute ion be included in the same model of electric polarization (convergent or divergent) as the substituted ion. The electrocardiogram and mechanogram of the isolated frog heart were observed. The heart was perfused with a modifier Ringer solution in which some of the normal component ions were replaced with other ions belonging to the same principal subgroup in Mandeleev's Table. The necessary condition provided by the model for two ions of different types to have a resemblance in their physiological activity was confirmed by the results of the experimental data.

Action Potentials↗
PubMedDate not supplied

Why there are only levo amino acids in the chemical composition of the living organisms.

In the structure of the DNA-histone system there are three kinds of elements which present spatial asymmetries: a) the D-deoxyribose molecules; b) the two strands of DNA which are wound counter-clockwise around the helical axis; c) the levo amino acids of the histones. This paper presents data and arguments which demonstrate that all these spatial asymmetries are interdependent and compose a unique system.

Amino Acids↗
PubMedDate not supplied

The energy transductions at the level of the acetyl-coenzyme A and of cytochrome molecules.

According to the model presented in this paper, the free energy necessary to the synthesis of the ATP molecules is delivered by a unique mechanism. This mechanism consists in the formation of an (Y:X) orbital, which turns with an angle, having the X atom as a pivot point, such that the Y atom is left out from the covalent bond and is replaced by a proton, released from a water molecule. Thus, a new (X:H) orbital is formed. In this first stage, within the newly formed (X:H) orbital the proton is situated at an internuclear distance equal to the length of the hydrogen bond (X...H). Then, the proton moves towards the nucleus of the X atom until it reaches the internuclear distance corresponding to the minimum energy. By the proton displacement, the two electrons of the (X:H) orbital arrive on an excited state level. Then they fall on their corresponding fundamental orbital, releasing two waves of electronic excitation. The two waves of electronic excitation are further transmitted to an acceptor of energy molecule.

Acetyl Coenzyme A↗
PubMedDate not supplied

The energetics of the active ionic transport across biomembranes.

A model of the energetics concerning the active ionic transport across biomembranes is presented. According to this model, the transfer of energy is made between a donor molecule and a receiver molecule, this being the manifestation of some electronic transitions, with the release, transfer and storage of two quanta of electronic excitation. The transfer of energy is accompanied by an exchange of ions between the donor molecule and the receiver molecule. If the two coupled molecules are fixed in the structure of a biomembrane, this ionic shift produces an active ionic transport across the respective membrane. The energy necessary to the accomplishment of the active ionic transport results from the difference between the energy released by the donor molecule and the energy stored by the receiver molecule.

Adenosine Triphosphate↗
PubMedDate not supplied

Energy and muscular contraction.

In this paper, a model of the chemical energy conversion into mechanical energy is presented. According to this model, for each stage, the transfer of the energy is produced in the framework of a polymolecular system composed by a donor molecule, an enzyme and an acceptor molecular couple. The energy is released in the form of two quanta of electronic excitation. The transfer of the energy determines the change of the orbital directions, as well as the ionic constellations previously fixed at the level of the donor molecule and at the level of the acceptor molecular couple. Subsequently, an allosteric modification of the enzyme which connects the donor with the acceptor molecular couple is produced. The conversion of the chemical energy into mechanical energy is explained by means of the ions movement and by the conformational changes of the enzymes involved in the processes of the energy transfer.

Adenosine Triphosphate↗
PubMedDate not supplied

The synergism and antagonism of cations.

The excess of the potassium, magnesium or hydrogen ions, as well as the diminution of the sodium ions concentration in the perfusion fluid can block the electrical and mechanical activities of the isolated heart of frog. These effects can be eliminated by a concomitant increase in the concentration of the calcium, sodium, or hydroxyl ions. The above-mentioned results suggest the existence of two types of ionic constellations, which are antagonistic: one formed from magnesium and potassium ions and functioning in a medium with an acid pH, and another one formed from calcium and sodium ions and functioning in an alkaline medium.

Animals↗
PubMedDate not supplied

Consideration on the genetic code.

In this paper there are presented data and arguments which indicate that the genetic code also contains the information for the assembling of the trinucleotides and amino acids in the DNA-histones system, which works as an intra-cellar computer.

Genetic Code↗
PubMedDate not supplied

The role of the sodium, potassium, magnesium and calcium ions in the transfer of energy at the level of the ATP molecule.

According to our model, in the stage which precedes the delivery of energy from the high-energy bond, one calcium ion and two sodium ions are fixed by the phosphates of the ATP molecule. In this way, a triangle of ions with the peak situated near the high-energy bond is formed. This triangle is an electric polarizing system, which directs the electronic orbitals of the phosphates in two diverging directions, starting from the calcium ion and going to the two sodium ions. The above-mentioned polarization helps, at the opportune moment, the breaking of the high-energy bond and the delivery of two waves of electronic excitation. In the stage which precedes the recovery of the high-energy bond, one magnesium ion takes the position of the calcium ion, and two potassium ions replace the two sodium ions. These ions form a polarizing system, which directs the electronic orbitals of the ADP and phosphoric acid molecule in two converging directions, starting from the two potassium ions and arriving at the magnesium ion. This polarization favours the building of the high-energy bond, when two waves of electronic excitation arising from a donor molecule arrive at the level of the two phosphates which must be united.

Adenosine Triphosphate↗