Mass-to-charge ratio refers to the molecular or atomic mass number and "z" to the charge number of the ion; however, the quantity of "m"/"z" is dimensionless by definition. An ion of 100 atomic mass units ("m" = 100) carrying two charges ("z" = 2) will be observed at "m"/"z" = 50. In the 19th century, the mass-to-charge ratios of some ions were measured by electrochemical methods. In 1897, the mass-to-charge ratio of the electron was first measured by J. J. Thomson. By doing this, he showed that the electron was in fact a particle with a mass and a charge, and that
Ribonucleoprotein particle Ribonucleoprotein particle A ribonucleoprotein particle or RNP is a complex formed between RNA and RNA-binding proteins (RBPs). The term RNP foci can also be used to denote intracellular compartments involved in processing of RNA transcripts. RBPs interact with RNA through binding motifs. Aromatic amino acid residues in this RNA binding motif result in stacking interactions with RNA. Lysine residues in the helical portion of RNA binding proteins help to stabilize interactions with nucleic acids. This nucleic acid binding is a result of the force of attraction between the positive electrical charge of lysine side chains and the negative electrical charge