Author Archives: aron engelhard

Let’s talk to our cells!

We are one step closer to achieve communication with those 37.2 trillion tiny components that make up our bodies. If you have ever wondered how the human body is capable of doing impressive amounts of chemical work without us even thinking about it, now you can understand it! Our bodies are efficient in converting energy, and communication among our cells is key to the understanding of all the basic processes that govern our life.

Cells often communicate via receptors made of sugars, that are exposed outside of their membranes. Such processes are often carried out by tiny sugar molecules that interact with those in their specific target. Recently, a team of researchers from The University of British Columbia published a synthetic method for modified sugars with incredible potential. In other words, it is now possible to obtain reliable materials to applications in cellular communication, metabolism and other biochemical processes.

 

Figure 1: Structural representations of the transformation of sugars carried out by the researchers. Adapted from ACS Catalysis

 

This method was developed by using clones of genetically modified bacteria to express enzymes that are capable of modifying the sugar in accordance to the interest of the researcher. To achieve this, the scientists screened a library of 175 genes of the species E.coli that encoded variations of enzymes that can be used to catalyze selective chemical reactions in sugars for creating glycosidic bonds.

Computational representation of a hydrolase, an enzyme that breaks sugars. Adapted from Wikipedia

Enzymes are proteins that provide a path of a biochemical reaction to occur more efficiently. They are relatively easy to obtain and work with; however, they are specific to their target substrates which limit the extent in which their capabilities can be exploited. The scientists solved this issue by modifying the internal composition of the enzymes to improve the diversity of products in a process called selective mutagenesis. With the aid of this technique, the investigators obtained all variants that were tested in this experiment.

Schematic representation of bacterial transformation and cloning. Adapted from Griffiths et a (2000)

As the use of biotechnology increases, the understanding of our microscopic world becomes a major tool for scientific development. In this case, E.coli cells are essential since bacteria are inoculated with synthetic versions of genes that encode these enzymes and are then used as living machineries for protein production.

It is worth to mention that transformations of sugars were already reported. Nonetheless, previous methods rely on the use of expensive reagents as catalysts, which represent  a major cost and are not widely accessible. This new approach opens a significant area in biochemical research. As technology improves to newer and more accessible  methods, the diversification of these enzymes could develop new approaches for interaction with cell receptors that could enable us to understand what our cells have to say.

-Aron Engelhard

Journal Source:

Armstrong, Z.; Liu, F.; Chen, H.-M.; Hallam, S. J.; Withers, S. G. Systematic Screening of Synthetic Gene-Encoded Enzymes for Synthesis of Modified Glycosides. ACS Catalysis 20199 (4), 3219–3227.

 

Inexpensive and rapid test to detect Lyme disease

A Great Challenge

Lyme disease is the most common vector-borne infectious disease in North America and Europe. Caused by the spirochete bacterium Borrelia burgdorferi, it is characterized by a rash in infected skin and leads to major symptoms if left untreated. Though many tests have been developed to diagnose this disease, the currently available tests are expensive and lack sensitivity (true positive rate) when it comes to the early stages of the infection.

 

Fortunately, a team of scientists from The University of California, Los Angeles, has recently developed a new inexpensive and trustful way of detecting this infection. They claim that this new procedure does not need previous training to be implemented, and that its sensitivity can be greater than 90%.

Figure 1: Lyme disease testing procedure. Adapted from ACSNANO

How does it work?

Figure 2: Illustration of the complexed reactions that lead to identification of the lyme disease. Adapted from ACSNANO

This novel test consists of a paper based multicomplex vertical flow assay, where small paper layers are covered in various disease-specific target proteins that interact with different antigens present in human samples. The protein-antigen interaction results in an observable change in colour. Upon the completion of the test, they generate a colour pattern that can be analyzed by a computer or even a smartphone. This allows possible diagnosis of the disease within minutes and increases specificity (true negative rate) and sensitivity in its early stages. The test has also been optimized with positive and negative controls to avoid false diagnoses, and it is enclosed in a 3D printed case for easy handling.

 

Major Improvements to Technology

Figure 3: Reported data on test sensitivity, specificity and Area Under the Curve. Adapted from ACSNANO

Previously used examinations could cost up to 400 USD per test, and their average time for diagnosis is currently over 24 hours. They also have very low sensitivity to the early stages of the disease, with values of less than 50% being reported. As mentioned by the authors, this assessment has a material cost of 0.42 USD per test which greatly reduces costs for diagnoses. They also report values of sensitivity of over 90% in early stages of Lyme disease and a specificity value of 87%. Nonetheless, this team of researchers have demonstrated the correct diagnosis of the disease in a matter of minutes making this process efficient, easy and available to the public at a reduced cost.

 

-Aron Engelhard

A greener approach to organic synthesis with reduced organic waste

It may sound counterintuitive, but it is in fact a reality. Organic solvent waste is one of the main contributors to pollution generated by the pharmaceutical industry worldwide. These substances are widely used in the preparation of drugs and other vital compounds, and recycling them represents a great challenge for many other industries. Fortunately, a team of researchers from the University of California Santa Barbara, has figured out a way to dramatically reduce the use of organic solvents in widely used synthetic procedures using micellar nano-reactors.

Formation of a Micelle Nano-reactor in aqueous medium. Adapted from https://www.kruss-scientific.com.

It is now possible to perform synthetic procedures in an inorganic solvent, such as water. The key aspect of this technology is the use of functionalized Vitamin E derivatives as nano-catalytic centres that enable organic molecules to react in an inorganic medium. Vitamin E is a lipid-soluble compound, when functionalized, it is able to form micelles in an aqueous environment that dissolve organic compounds as well as other reactants. Reactions take place inside each of these micelles due to their lipophilic character, enabling the entire process to be carried out in water.

Structure of Micellar nano-reactor. Adapted from ACS.

So far, this technique has been used in a wide variety of reactions which include but is not limited to: Cross-couplings, olefin metatheses, trifluoromethylations and aminations, with high yields, little waste and reduced costs. In many industries, waste is measured in E factors. An E factor is defined as the quotient between the amount of produced waste in kg, divided by the amount of desired product obtained by the process.

E Factor comparison between pharmaceutical methods and researchers work for cross coupling reactions. Adapted from Green Chemistry

 

The nano-reactor technology has demonstrated a decrease in E factors for as much as 98%, meaning that this method could drastically change the effect of big corporations in our environment.

-Aron Engelhard

Engineered bacteria is capable of feeding through atmospheric CO2

A study led by a team of researchers from the Weizmann Institute of Science in Israel has confirmed a recently developed fully autotrophic E.coli strain whose generated biomass is solely derived from a greenhouse gas.

E. coli bacteria cells. Source: Livescience

CO2 accumulates in our atmosphere and it is commonly used by plants to generate sugars for their sustainable growth.This promising strain could be used as a renewable food source and energy storage.

Hacking Metabolism

An originally heterotrophic bacterium was successfully converted into an autotrophic organism. Scientists rewired their core metabolic pathway, introduced heterologous (non-native) genes and Formate as an accessible electron donor, providing such organism with the required enzymatic machinery to effectively convert inorganic carbon into biomass under physiological conditions. Furthermore, the carbon source of nearly all biomass produced was confirmed to atmospheric CO2 with isotopic labeling techniques.

Summary of photosynthetic pathway from an engineered bacterium cell. Source: Cell

Photosynthesis is a process common to plants and some microorganisms, and it is the first step in the food chain. Evolutionarily speaking, this transformation is considered a major accomplishment since these two metabolic pathways are very distinct. Autotrophs and heterotrophs diverged millions of years ago, although some organisms with both metabolic routes are known to exist.

Summary of transformation. Source: technologyandus.com

 

Next Steps

Regulation of CO2 in our atmosphere has become one of the most important challenges in today’s era.  We are constantly looking for sustainable ways of producing food, fuel and biochemicals, and this study presents a new yet promising approach to reduced carbon emitting food sources with a broad spectrum of fields in which this technology can be applied.

There is great diversity in the compounds that can be synthesized through this process and its deep understanding may have a large impact in the future of a new carbon neutral world.

This finding also denotes the flexibility of metabolic processes to support life as mentioned by the authors:

– “This rapid trophic mode transformation showcases the outstanding plasticity of metabolism and demonstrates the power of the framework described here for designing and implementing the rewiring of cellular metabolism.”

-Aron Engelhard