Experimental history

We present here the mechanisms for four enzymes chymotrypsin, hexoldnase, enolase, and lysozyme. These examples are not intended to cover all possible classes of enzyme chemistry. They are chosen in part because they are among the best understood enzymes, and in part because they clearly illustrate some general principles outlined in this chapter. The discussion concentrates on selected principles, along with some key experiments that have helped to bring these principles into focus. We use the chymotrypsin example to review some of the conventions used to depict enzyme mechanisms. Much mechanistic detail and experimental evidence is necessarily omitted no one book could completely document the rich experimental history of these enzymes. Also absent from these discussions is the special contribution of coenzymes to the catalytic activity of many enzymes. The function of coenzymes is chemically varied, and we describe each as it is encountered in Part II. 

Marie Boas, Robert Boyle and Seventeenth-Century Chemistry (Cambridge University Press, 1958), 133-141. See also A. Albert Baker, A History of Indicators, Chymia 9, 1964, 147-167 Peta Dewar Buchanan, J. F. Gibson, and Marie Boas Hall, Experimental History of Science Boyle s Colour Changes, Ambix 25, 1978, 208-210 William Eamon, New Light on Robert Boyle and the Discovery of Colour Indicators, Ambix 27, 1980, 204-209. 

Buchanan, Peta Dewar, J. F. Gibson, and Marie Boas Hall. Experimental History of Science Boyle s Colour Changes. Ambix 25, 1978, 208-210. 

The following three sets of findings summarise selected aspects of progress in the unraveling of a new PPP reaction sequence in liver that was found to measure 20-30% of total glucose metabolism. The experimental history of these events is fully recorded by Williams et al. in References 42 and 53 and in Reference 1 (pp. 766-790). 

Trommsdorff s Journal der Pharmacie, apothecaries participated in the regular communication of the community of chemists.1191 would like to extend Hufbauer s argument to include not only communication and justification, but also apothecaries investigative practice in the laboratory. The possibility of publishing papers may have provided an incentive for more careful observation in the pharmaceutical laboratory and more systematic and extended chemical investigation. It may have reinforced a trend, which hinged on the correspondence between the material culture of the pharmaceutical and the chemical laboratories, to shift from the pharmaceutically useful to chemical analysis and the experimental history of substances.120 Thus chemical journals may have fed back into the actual practice of apothecaries and contributed to the emergence of the persona of the apothecary-chemist on many different levels. 

This attitude accorded with the venture of natural and experimental history of the time (see footnote 92). 

Black commented on good and bad marl as early as the 1760s Black, Lectures 176718, 58. Agricultural topics were also covered by leading chemists like Herman Boerhaave and Pierre Macquer, both of whom were required reading for chemistry course run by Cullen and Black. Boerhaave s interest in the chemical composition of plants is addressed in Ursula Klein, Experimental history and Herman Boerhaave s chemistry of plants, Studies in the History and Philosophy of the Biomedical Sciences 34, 2003, 533-67. 

Flynn and Dickens (124) described a TG method in which the magnitude of a rate-forcing variable such as temperature, pressure, gaseous flow rate, gaseous composition, and so on is jumped by discrete steps. This method can be used to determine kinetic relationships between the rate of mass-loss and thejpmped variahlft. The method avoids the disparate effects of separate experimental histories in methods in which two or more experiments are compared and also the necessity for guessing the complex rate versus the extent of reaction relationship. 

The degradation of the composite laminates can be modelled as simple strength criteria for fibres or matrix, before delamination occurs. Eigure 9.19 shows the test force history for a 200 x 200 mm plate and the various numerical EE (77) predictions (Davies et al. [42]), The hnear elastic case does get the time of the event but underestimates the peak force by a factor of 3. The damaged EE prediction overestimates the force but does get the departure from the linear solution correctly. The fuUy degraded solution (with much fibre failure) does match the experimental history. Delamination was confined to one interface near the mid-plane as the C-scan image indicates. 

An explicit program of an experimental history first arose in the early seventeenth century when Francis Bacon (1561-1626) became its most prominent spokesman. Bacon outlined his ideas of an experimental history historia experimentalis) in a text entitled Preparative towards a natural and experimental history, which was published in 1620 in the same volume with the Novum Organon. Experimental his-... 

In Bacon s view, experimental history complemented natural history, since it explored the possibilities and limits of movements and other alterations of things. The history of arts, he emphasized, exhibits things in motion, and leads more directly to practice. Boyle echoed Bacon s words, asserting that there are very many things made by Tradesmen, wherein Nature appears manifestly to do the main parts of the Work and further he stated that... 

Robert Boyle in particular made efforts to demarcate experimental history from its philosophical counterpart that is, experimental philosophy. For example, in his Experimental History of Colours (1664), he asserted that his present work would... 

Boyle [1999] vol. VI p. 467. In another essay on the Usefulness of Natural Philosophy (1671), Boyle stated that it is my main business, to take all just Occasions, to contribute as much, as without indiscretion 1 can, to the history of Nature and Arts. Of the truth of experiments, he continued, one may be easily satisfyed, by inquiring of Artificers about it, and the particular or more circumstantial accounts I give of some of their experiments, I was induc d to set down by my desire to contribute toward an experimental History (ibid. p. 396). 

Furthermore, Bacon s and Boyle s emphasis on the importance of technical artifacts and artisanal operations for the writing of an experimental history was embedded in another ongoing culmral movement that revalued the role played by the methods and accomplishments of artisans for the acquisition of natural knowledge. For example, in a treatise published in 1531 Juan Luis Vives (1492-1540), friend of... 

See Pomata and Siraisi [2005] p. 27. It should be noted that Pomata and Siraisi do not distinguish here between experimental history and experimental philosophy, as we do. Experimental philosophy also highlighted detailed description, but its objects of inquiry were not particulars. Furthermore, the meaning of the objects of inquiry in experimental philosophy was constituted in philosophical discourse and hence thoroughly underdetermined by observation. See also below in this chapter the section on experimental inquiries into the imperceptible dimension of chemical substances. ... 

The distinct style of experimental history can be discerned especially well in the history of chemistry from the seventeenth century until the early nineteenth century. In the chemistry of this period, experimental history meant a collection of facts about a great number of substances from all possible practical areas, ranging from artisanal sites and everyday life to the academic chemical laboratory. Of course, only a few eighteenth-century chemists ever read Bacon s writings or subscribed explicitly... 

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