Psychology and philosophy are intertwined disciplines, and the Greeks proposed many theories and philosophies of the human mind. The origins of psychology can be traced back to the Ancient Greeks, along with the Romans. The root word ψυχή (‘psichy’ or psyche), means “life”, “soul”, and “heart” in Greek. Psi is also the first letter in the Greek word for psychology: Ψυχολογία.
Psi is the 23rd letter in the Modern Greek alphabet. The capital-letter version of psi (Ψ) is generally preferred over the lower-case psi (ψ). Extensive description of torsional angles.The symbol for psychology or psychology studies is Ψ, which is the Greek letter psi and the shape of a trident or pitchfork.Excellent description of torsional angles by Damir Zucic.Animation of Phi and Psi rotations by David Sanders.Dihedral/Index which lists many tutorials and resources about the Ramachandran principle, and phi and psi angles in proteins.
Since the does not leave the plane of the peptide bond, the rotation of the α-carbon changes the angle of the yellow plane relative to the plane of the peptide bond (orange and purple), and thus sets the the psi for Leu47. The (larger diameter sticks) can be rotated to set psi for Leu47. With this being the case the psi for Leu47 can not be set by rotating this peptide bond plane because in doing so the Ile phi value would change. Notice that the orange plane involved in setting phi = -149 o is in the same peptide bond plane as the purple plane that sets psi for Leu at -34 o. An amino acid needs to be bonded to in order to have values set for both psi and phi, for that reason the two terminal amino acids do not have values set for these angles. The orange plane is part of the between Ile and Leu (blue plane), and the angle between the blue and yellow planes is phi. The purple plane is part of the (side chains removed for clearer viewing) between Tyr and Ile (red plane), and the angle between the red and yellow planes is psi. The yellow plane serves as the references in measuring the two angles. Notice the three colored triangular planes. The initial scene shows phi and psi values for Ile. Of two other peptide bonds, and then using the technique described above identify the atoms contained in and the numerical values of the φ and ψ angles of the α-carbon connected to these two planes. that you correctly determined direction of rotation and the values of φ and ψ. After rotating the structure so that the four atoms can be clearly seen, measure and display the numerical value of ψ using the technique described above. (If the structure rotates in the course of clicking on the atoms or if you encounter some other problem, re-click on the green link 'four atoms' and restart clicking on the atoms.) The which constitute a ψ are an amide nitrogen, a carbonyl carbon, an α-carbon and a second nitrogen. After toggling off spin and rotating the structure so that you can clearly see that you are not clicking on a transparent atom, determine and display the numerical value of φ by double clicking on a carbonyl carbon of the angle, single clicking on the next two atoms and then double clicking on the second carbonly. The making up φ are a carbonyl carbon, the connecting α-carbon, an amide nitrogen and the next carbonyl carbon (all marked with green halos). 1 Determining values for phi (φ) and psi (ψ)ĭetermining values for phi (φ) and psi (ψ).