Introduction to Carbohydrate Biotechnology

The study of carbohydrates has been neglected in favor of consideration of investigation of the properties and functions of the more obviously important classes of biochemicals, nucleic acids, and proteins. There are various reasons for this: the concept of carbohydrates as relatively boring materials that are important as major food components and as structural molecules in cell walls but without subtlety of function, as well as the sheer difficulty of working with them. During the evolution of molecules the new availability of monosaccharides provided nature with a class of molecules that could be used as the building blocks for macromolecules of a complexity far in excess of that which can be achieved by polymerizing amino acids. With four (in pentoses) or five (in hexoses) hydroxyl groups available for reaction on each monomer, polymers with various degrees of branching are possible using only a single sugar as monomer, but some 25 different monomers actually occur in naturally occurring carbohydrates, making a staggering, unimaginable number of combinations possible. Carbohydrates thus can act as the repositories of enormous amounts of information: elucidation of the language in which this information is coded may well occupy biotechnologists and experts in linguistics well into the next century. They will be thankful that not all the sugar structures possible are actually used in biological molecules, but they will have to remain aware that nature has tools available that have not been employed (probably!).