Polymer Biochemistry

Life is based on polymers. Of course, the most well-known example is DNA, because nowadays every child knows that DNA contains genes that form the code of life. DNA, like RNA, is a long unbranched polymer made of nucleotides. This information is used to produce a different type of polymers, the proteins. Also these polymers are unbranched chains, but consist of amino acids. These chains have the amazing capability to fold into specific three-dimensional structures, which enable them to act as little molecular machines.

However, as important as these two polymers are, a third class of polymers is usually less considered but at least equally important: polymers made of sugar. The most prominent example is the substance, which provides half the caloric uptake of humankind: starch. In contrast to the examples above, starch possesses a complex branched structure, but contains only a single type of monomer, namely the sugar glucose. Glycans, as the sugar-based polymers are called, play central roles in many aspects of life. Energy storage is certainly the most dominant role if measured by mass, but glycans are also knwon to be involved in cell-cell signalling processes, they are central components of cell walls giving for example trees the stability they need to grow over 100m, they even play a role in immune defense.

The formation and the degradation of polymers, in particular branched polymers such as glycans, is a complex process involving a large number of enzymes. Some glycans, such as starch, are insoluble, so synthesis and degradation processes take place on a complex surface - and not in solution, as is usually considered when investigating biochemical processes in isolation. Moreover, many enzymes involved in glycan metabolism, perform a certain well-defined reaction pattern, but they are extremely felxible when it comes to the exact nature of their substrates. Often, enzymes just recognise a certain end of a polymer but do not care how the rest looks like. This leads to the complication that such an enzyme can catalyse an enormous number of distinct chemical reactions.

All these issues make it very complicated to find consistent and unifying descriptions for the enzymes acting on polymers. In our research, we aim at developing new theoretical concepts, which allow us to understand the action of these enzymes. With such an understanding, we hope to be able to control polymer synthesis and degradation processes with such a precision that we can design tailored polymers for specific purposes.

A recently awarded collaboratiev project is DesignStarch, funded under the ERA-CAPS scheme by the DFG, the BBSRC (UK) and the SNF (CH). In this project, we apply theoretical and synthetic approaches to reconstruct the process of starch synthesis in yeast, an organism that usually does not produce starch. By this engineering approach, we hope to gain deeper understanding about the interaction of the various complex biochemical and biophysical processes and to be able to design starches with desired properties in the future.

Contact: Dr. Adélaïde Raguin, Jun.-Prof. Dr. Oliver Ebenhöh

Key Publications

  1. Kartal O, Ebenhöh O. A generic rate law for surface-active enzymes. FEBS Lett. 2013 Sep 2;587(17):2882-90. doi: 10.1016/j.febslet.2013.07.026. Epub 2013 Jul 23.
  2. Kartal O, Mahlow S, Skupin A, Ebenhöh O. Carbohydrate-active enzymes exemplify entropic principles in metabolism. Mol Syst Biol. 2011 Oct 25;7:542. doi: 10.1038/msb.2011.76.

Further reading

Verantwortlich für den Inhalt: E-Mail sendenPascal Spinnrath