The chemistry and biochemistry of insulin

The protein hormone insulin occurs widely in the animal kingdom. Although its biological function is always the same, its amino-acid composition varies widely. Insulin consists of two polypeptide chains, which are linked by three cystine residues to form a bicyclic system with a 20-membered and an 85-membered ring. The protein crystallizes in various forms with foreign ions. In solution, insulin normally forms aggregates of 2n molecules. The hormone can be regenerated from the separated polypeptide chains, and its total synthesis has been achieved in a similar manner from synthesized peptide chains. In the biosynthesis of insulin, the two chains are evidently built up separately and subsequently linked together. Insulin promotes the synthesis of glycogen, fat, and protein in the organism; insulin deficiency leads to an increase in the blood-sugar level. At the molecular level, the mechanism of action of the hormone is still unknown. Current hypotheses are discussed. No specific active center has so far been detected in the insulin molecule, which contains several antigenic regions.     

Recent chemistry and biochemistry of bile pigments

Bile pigments are not merely waste products of the degradation of hemoglobin, but have specific functions in plants and lower animals, in which they occur in the form of chromoproteins (biliproteins). Chromic acid degradation under controlled conditions is particularly suitable for structural investigations. In the case of the phycobilins (bile pigments of red and blue algae), not only have the structures been established, but the linkages with the proteins have also been located.     

Microfluidics: Applications for analytical purposes in chemistry and biochemistry

In this review, we present recent advancements and novel developments in fluidic systems for applied analytical purposes in chemistry, biochemistry, and life science in general that employ and reflect the full benefits of microfluidics. A staggering rise in publications related to integrated, all‐in‐one microfluidic chips capable of separation, reaction, and detection have been observed, all of which realise the principal of micro total analysis systems or lab‐on‐a‐chip. These integrated chips actively adopt the scaling law concepts, utilising the highly developed fabrication techniques. Their aim is to multi‐functionalise and fully automate devices believed to assist the future advancements of point‐of‐care, clinical, and medical diagnostics.     

Deoxyribonucleotides: the unusual chemistry and biochemistry of DNA precursors

Deoxyribonucleotides, monomers of macromolecular DNA and the chemical matter of genes, have received surprisingly little attention among chemists and molecular biologists alike, although their origin, properties, and mechanism of enzyme-catalyzed formation bear unique chemical traits which are the basis of DNA replication. Apart from providing insights in bioorganic free radical chemistry, present interest in deoxyribonucleotides stems from the expected demand of hundreds of kilograms per year for DNA chips and antisense constructs used in gene therapy, difficult to produce by conventional methods. A novel approach towards deoxyribonucleotide, and hence DNA formation in a putative primordial 'RNA world' has also recently emerged.     

Oxidation chemistry and biochemistry of some biologically important purines and indoleamines

The electrochemical oxidation of 7-methyluric acid and 5,6-dihydroxytryptamine (5,6-DHT) in aqueous solutions has been studied. The oxidation products have been separated and characterized using melting point, mass, ¹H nuclear magnetic resonance and spectral studies, and tentative mechanisms for the oxidation have been suggested. One of the oxidation products of 5,6-DHT, i.e. 2,7′-bi(5,6-DHT), has been found to produce a substantial neurotoxic effect in mice brain.     

Solvent effect theories: Quantum and classical formalisms and their applications in chemistry and biochemistry

The quantum chemical and mathematical background and some new approaches to the modeling of solvent effects are described.     

Penta-coordinate phosphorous compounds and biochemistry

The relationship between penta-coordinate phosphorus compounds and biochemistry is briefly reviewed. Some interesting phenomena such as peptide formation, ester formation, ester exchange on phosphorus and N to O migration occur at room temperature when the amino group of amino acid is associated with phosphoryl group. Serine or threonine in conjugate of nucleo-side-amino acid could recognize different nucleobases. N-phosphoryl Histine and Ser-His dipep-tide could cleavage nucleic acid, protein and ester in neutral medium. It is found that the above phenomena all undergo penta-coordinate intermediate of phosphorus atom, which is proposed as the key factor to determine their activities.