Module 1 : Introduction to Bioorganic Chemistry

Lecture 1 : Defining Bioorganic Chemistry

1.1.4 Bio-organic Chemistry-A Borderline Science-Its Multiple Origin:
  1. Enzyme Chemistry: For some hydrolytic enzymes the catalyzed reaction has been translated already into a series of normal organic reaction steps. At the same time organic chemists are mimicking the characteristics of enzyme catalysis in model organic reactions dealing with both the rate of reaction and specificity.
    Investigations, involving metalloenzymes and cofactors, the contiguous areas of bioorganic and bioinorganic chemistry also merge.
  2. Nutritional Research: Knowledge of biochemistry enables us to recognize the factors essential in the human diet, and their structures and syntheses with the help of organic chemistry led to the recognition of the modes of action of the so-called vitamins and related cofactors, or coenzymes.
  3. Hormone Research: Secreted factors that exert a stimulatory effect on cellular activity, the hormones, could be better understood at the molecular level once their structure determinations and syntheses made them available in reasonable amounts with the help of organic chemists.
  4. Natural Products Chemistry: Concepts of the biogenesis of natural products played, and continues to play, a major role in the development of bioorganic chemistry. The classical chemistry of natural products with its characteristic triad of isolation, structural proof and total synthesis is an evident, but is a purely organic ancestor. Likewise, inquiry into the biosynthetic pathways for the same natural products is plain biochemistry. But when the total synthesis of a natural product explicitly is based upon the known route of biosynthesis or if the biosynthesis has been translated into structural and mechanistic organic chemical language, one is clearly dealing with bioorganic chemistry.
  5. Molecular Recognition: The term molecular recognition refers to the specific interaction between two or more molecules through non-covalent bonding such as hydrogen bonding, metal coordination, hydrophobic forces, van deer Waals forces, pi-pi interactions, electrostatic and/or electromagnetic effects and is purely physical organic chemistry origin. The host and guest involved in molecular recognition exhibit molecular complementarities. Molecular recognition plays an important role in biological systems and is observed in between receptor-ligand, antigen-antibody, DNA-protein, sugar-lectin, RNA-ribosome, etc. An important example of molecular recognition is the antibiotic vancomycin that selectively binds with the peptides with terminal D-alanyl-D-alanine in bacterial cells through five hydrogen bonds. The vancomycin is lethal to the bacteria since once it has bound to these particular peptides they are unable to be used to construct the bacteria’s cell wall. Therefore, the composite term, biophysical organic chemistry, has been used as a detailed descriptor in molecular recognition.
  6. Protein Chemistry (sequencing) vs. Application of Reagents: A simple chemical applied according to a well recognized concept can be responsible for a great advance in biological chemistry. Thus, through the reaction of cyanogens bromide, Bernhard Witkop translated neighbouring group participation into selective, limited, non-enzymatic cleavage at methionine in a peptide chain.
  7. Reagents vs. Modern Biotechnology: Application of the reagent has aided not only the correct sequencing of peptide segments of many proteins but also the production, through genetic engineering, of human insulin by means of a methionyl-containing precursor version at each step provides the basis of modern biotechnology: the, automated synthesis of polypeptide and polynucleotide chains and the sequencing of DNA and RNA.