The theory of van der Waals forces has now developed to a stage where it constitutes a powerful tool in theoretical investigations of many biological systems. In this review we shall consider both the theoretical and conceptual aspects of these forces with the emphasis on the way they may be involved in various biological processes.

The success of equilibrium thermodynamics in describing static phenomena has inspired many attempts to develop a rigorous thermodynamics of rate processes.

Spectroscopic probes have become powerful tools in analysing the correlation between structure and function of biological macromolecules. Though these spectral methods cannot give as circumstantial information about the anatomy of a biological structure as, for example, X-ray diffraction they can provide information on physical properties at defined loci in a macromolecule which are not accessible by other techniques. Most important, spectroscopic studies have provided means to study the dynamics of structural changes and interactions in time domains spanning from nanoseconds and less up to infinite time.

Until recently there has been very limited information concerning the molecular geometry and conformation of biogenic monoamines and this lack of knowledge has seriously hampered efforts to unravel the structure—function relationships at the molecular level. Nevertheless, several theories have been proposed regarding interaction between the monoamines and their receptor sites. This is especially true for the neurohumoral transmitters dopamine, noradrenaline (norepinephrine) and serotonin (5-hydroxytryptamine), the target areas of which seem to be specific not only in the sense of chemical structure but also from the steric point of view. The well-known differences in biological activity due to chiralty illustrate the importance of the three-dimensional architecture of the molecules and indicate also the presence of stereospecific receptor sites. A detailed knowledge of the conformation of the biogenic monoamines would not only elucidate the requirements upon a natural or synthetic monoamine for proper function but also give indirect information about the geometry of the receptor sites.

Mass spectrometric analysis of organic compounds was in the early 1950s done mostly for quantitative determination of petroleum products. The use of the mass spectrometer for qualitative analysis of solid organic material samples was shown by O'Neil & Wier (1951) and since then a continuous increase in mass spectrometric studies of different classes of organic compounds has been noted. After the gas chromatograph was developed by James & Martin (1952) the quantitative analysis of complex mixtures of organic compounds was possible and after a few years the gas chromatographic method was considered as routine. The first connection of a gas chromatograph (GC) to a mass spectrometer (MS) was made by Holmes & Morell (1957). They studied gases using a splitter system where only a small part or less than 1% of the effluent from a packed column was transferred to the ion source of the mass spectrometer. The next step in GC—MS development was made by Gohlke (1959), who studied compounds of low molecular weight using capillary column directly connected to a time-of-flight mass spectrometer. This was possible due to the fact that the carrier gas flow rate could be limited to about 1 ml/min. To avoid the sample loss resulting from using a packed column with the splitter system a jet molecular separator was constructed as an interphase between the packed column and a mass spectrometer with magnetic sector analyser (Ryhage, 1964). Mixtures of fatty acids and of hydrocarbons with a molecular weight of up to about 420 were studied. In this study spectra were taken at irregular intervals.

The compound 5-bromouracil (BrU) may be incorporated into DNA in place of its analog thymine. This review is concerned with the photochemical lesions produced by the action of ultraviolet light on such BrU-DNA, and consequent biological effects of such lesions.

Few fields of biochemistry have seen such widespread applications of physical theories and techniques as that of biological oxidation. There are obvious reasons for this. Oxidation-reduction reactions form the foundations of bioenergetics, an area which can only be understood in terms of thermodynamic theory. Most components of the mitochondrial respiratory chain contain transition metals, and these elements and their chemical environment can often be studied by modern spectroscopic methods, such as electron-paramagnetic resonance (EPR). The relation between spectroscopic properties and chemical structure of metallo-proteins, e.g. haem proteins, represents one of the few branches of present-day biochemistry to which quantum mechanical calculations can profitably be applied (see, for example, Zerner, Gouterman & Kobayashi, 1966).

This review takes the regulation of breathing in man as an example of a highly developed and much studied control system in higher mammals.

It is well known that excited states may be generated chemically in biological systems as evidencex and by the phenomenon of bioluminescence and it is natural to suspect that they may also be generated and used in dark processes (Szent-Györgyi, 1941; Steele, 1963; Cilento, 1965; White & Wei, 1970; White et al. 1971). Förster (1967) has pointed out that electronic excitation and subsequent transfer processes may occur in biological dark systems despite the fact that the energy available from enzymic processes is too low to excite aromatic amino acids and other biochemical structures. Hastings (1968) suggests that in some organisms light emission is just an alternative to the formation of an active species.

In the article ‘Molecular interactions and structure as analysed by fluorescence relaxation spectroscopy’ by Rudolf Rigler and Måns Ehrenberg, which appeared in Quarterly Reviews of Biophysics 6, 2 (1973), pp. 139–199, printing errors occurred:

P. 145, 1.8:should read

P. 153, 1.20: … coefficient in some cases… should read …coefficient and in some cases…

P. 159, 1.13: …, φ2(λ′) should read …, φλ(λ′)…

P. 190, 1.4: … as well as the signal-to-noise ratio,… should read … as well as of the signal-to-noise ratio,…