Cellular Machines


Why is in-vitro studies necessary? Life has always taken place in rather complex settings.  These days, everything that we know about various fundamental topics like enzyme mechanism, molecular recognition in biological molecules, as well as DNA replication are all the fruits of studies that were performed on proteins that are purified to certain standards.

An understanding of a molecule’s 3D structure makes it possible to determine ways in which this can be developed into something of function. Structural biology was first developed in the 50s when the myoglobin and the double helix of the DNA’s structures were successfully determined at their respective atomic resolutions. Today, after over 60 years of study and tens of thousands of structures, it is easy to look back at the humble beginnings of the field and the progress that it has achieved so far.

It’s a fact that there are so many things that were discovered regarding the protein structure and how they function over the years. For instance, it’s now possible to determine the hierarchical structure governing proteins set in a world that very much resembles that of Legoland. It is now easy to envision how globular proteins have certain secondary elements in its structure that then make up the basic domains or folded units that make up globular proteins.

Perspectives have also changed and shifted over time and many of the established rules then have sice been debunked and replaced with the latest findings in the field. Structural Biology first set out as a field where people are focused on globular proteins. It moved on to focus more on protein complexes which developed into such complex systems as the ribosome or the proteasome.

Among the more recent developments include the realization about how not every protein is actually made upon globular entities. It’s been discovered that many of these proteins are developed intrinsically. Many are even developed without any of the ordered structure that it has always been known for especially in situations where a partner is absent. This has only added even more complex layers to the overall perspective of the structural landscape of proteins.

All these achievements are only possible because of the development of more advanced techniques that now covers a wide range of resolution. This includes fiber diffraction and X-ray calligraphy— two techniques that are considered to be the most established of them all. There’s also the nuclear magnetic resonance in a liquid state, small-angle scattering, as well as cryo-electron microscopy. Another more recent introduction to the field is the technique using the nuclear magnetic resonance of solid-state along with mass spectrometry.

There are also notable changes to the modern perspective of protein structures. For instance, the idea that one protein has one function has long been scrapped. What used to be an exception in the form of moonlight protein, has now become the established rule. Moonlight proteins are those that adopt a variety of functions.

Moving forward, the field aims to understand the dynamic functions of full molecular machines with the goal of focusing beyond just static complexes description. As it is, the grand challenge for the next two or three decades would be to capture the secrets of cellular machines by reconstructing their intricate interactomes as well as getting all of their complexes characterized.