A hydrolytic derivative of the globulin edestin and its relation to Weyl's albuminate and the histon group.

  • Osborne, Thomas B. (Thomas Burr), 1859-1929.
Date:
[1900]
Catalogue details

Licence: In copyright

Credit: A hydrolytic derivative of the globulin edestin and its relation to Weyl's albuminate and the histon group. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    reviewed the reactions of the histons and concludes that for the present these may he defined as follows. In neutral solution the histons are precipitated by the cautious addition of ammonia, the precipitate in the presence of an ammonium salt very soon becoming' insoluble in an excess of ammonia. They give a pre- cipitate with nitric acid, which dissolves on heating and reap- pears on cooling. They are precipitated from neutral solution by heating, if their solutions contain some sodium chloride, not, however, if they are poor in salts. Neutral solutions of histons are precipitated by the alkaloid reagents and by solu- tions of ovalbumin and other proteins. In this group of bodies Bang includes goose-blood histon, thymus histon, scombron and globin. I have shown that edestan has all these reactions with the exception of the precipitation of the solution by heat in the presence of moderate quantities of neutral salts. This reaction could not be obtained with edestan as it is insoluble in water, and the aqueous solution of its chloride gives a precipitate with a very little salt which is insoluble in stronger saline solutions. The most important difference between these histons and edestan is that the former appear to be soluble in water when neutral, whereas neutral edestan is very insoluble in water, the reactions, which I have described, being given by aqueous solutions of its chloride. This combined acid, however, is present in such small proportion that it can be detected only in concentrated solutions by using very delicate litmus# paper, so that it might easily be overlooked were its pres- ence unknown. Bang gives no evidence that his solutions did not contain a similar proportion of acid and it seems prob- able that some of them at least did contain it, since the sub- stances were extracted by dilute hydrochloric acid and the solutions made “neutral” presumably to litmus, this indicator being the one commonly employed by physiologists for such purposes. That any near relation exists between edestan and the bodies enumerated by Bang as histon is not probable, except in the case of globin, which seems to be more nearly related to edestan than to the histons since globin is a true protein substance, obtained from haemoglobin by the action of acids under conditions similar to those leading to the formation of edestan. With thymus histon and with scombron, it would