July 30, 1903] 



NATURE 



THE CHEMISTRY OF THE ALBUMINS. 

 'TTHE composition and constitution of the albumins have 

 hitherto been studied ahnost exclusively from the 

 analytical point of view, and particularly by the examination 

 of the products of hydrolysis effected by either acids, 

 alkalies, enzymes, or putrefactive bacteria. 



Improved methods for the separation of these products, 

 due to Kossel, E. Fischer, and others, have led to the con- 

 ception of the complex albumin molecule as composed of a 

 large number of simple molecules, consisting to a great 

 extent of monamino- and diamino-acids and related com- 

 pounds (compare Nature, vol. Ixv. p. 90), united together 

 by some form of condensation, which involves an amino- 

 group, and is probably similar in nature to that which 

 occurs in the formation of the acid amides. 



The various members of the vast group of albuminous 

 substances may differ from one another in many ways, but 

 two of the chief points of difference appear to be the variety 

 of these component groups, and the numbers of them con- 

 tained in a single molecule. Thus a comparatively simple 

 albuminoid substance, such as silk when it is completely 

 hydrolysed, yields, among other products, the monamino- 

 acids, tyrosine, phenylalanine, leucine, alanine (amino- 

 propionic acid), and glycine (aminoacetic acid). Gelatin, 

 on the other hand, which is also comparatively simple in 

 composition, differs markedly from silk by the absence of 

 tyrosine, whilst oxyhaemoglo'bin, to take another instance, 

 yields tyrosine, but no glycine. 



By the incomplete hydrolysis of the fibroin of silk, more- 

 over, Prof. E. Fischer has obtained a substance which 

 appears to be a compound of aminoacetic and amino- 

 propionic acids. The formation of this substance is of 

 great interest, since it probably represents an intermediate 

 stage of the decomposition, and affords strong confirmation 

 of the view of the constitution of the proteid molecule which 

 has just been stated. 



Most of the final products of hydrolysis of the albumins 

 are familiar compounds which can readily be prepared by 

 synthetic methods, but very little has hitherto been known 

 of the more complex substances to be obtained by the link- 

 ing together of several of these molecules. It 'is in this 

 direction that Prof. Emil P'ischer has been working for 

 some time past, and he has contributed to the current 

 number of the Berichte an account of the highlv important 

 results which have already been attained. The plan of 

 attack consists in endeavouring to build up complex sub- 

 stances from the simple amino-acids by first introducing a 

 second molecule of the same or another acid, and then re- 

 peating the process as frequently as possible with each 

 successive product. 



The first step was taken some time ago by the production 

 of glycylglycine, NH,.CH,.CO.NH.CH...CO,H, from 

 glycme anhydride. This substance contains two molecules 

 of glycine united in the typical manner, and is the simplest 

 of the polypeptides, as these bodies have been named, 

 because of their assumed similarity to the peptones in 

 structure. To add a third link to the chain is, however, 

 a matter of difficulty, owing to the ease with which the 

 amino-group undergoes change. Two methods have, how- 

 ever, been found by means of which this can be accom- 

 plished. 



The first of these consists in building up the new amino- 

 acetic molecule by first introducing into the amino-group 

 the chloracetyl radical, Cl.CH,.CO. (bv the action of 

 chloracetyl chloride), and then introducing' the amino-group 

 by the action of ammonia, the final product being a crvstal- 

 line substance having the formula of a diglvcylelvcine 

 NH,.CH,.CO.NH.CH,.CO.NH.CH,.CO.H. A description 

 of the properties and reactions of this substance has, un- 

 fortunately, not yet been published. 



The other method consists in first of all introducing the 

 group .COXjH, into the amino-group of glycylglycine. 

 The resulting compound can then be converted into an acid 

 chloride, which readily reacts with the ester of glycine to 

 form the desired compound containing three glycine mole- 

 ' ules. A repetition of this process leads to the addition of 

 I fourth glycine molecule to the chain, the final product 

 which has hitherto been obtained being of the respectable 

 complexity shown bv the formula 



307 



CO2C2H5.NH.CH2.CO.NH.CH.J.CO.NH.CH2.CO.NH.CH2.CO2C2H5 

 NO. I 76 I. VOL. 68] 



(carboxethyl-triglycylglycine ester). This substance is 

 crystalline and is converted by ammonia into a crystalline 

 aniide, which gives, with an alkali and a copper salt, the 

 well-known biuret reaction, which is given by all the arnides 

 of this series, as well as by the albumins. The group 

 .COjCjH, combined with the amino-group cannot, so far, 

 be removed from the molecule, so that, until some means 

 of doing this is discovered, this method can scarcely be 

 expected to yield derivatives so closely related to the actual 

 proteids as those obtained by the method first described. 



Both methods obviously lend themselves to the production 

 of a great variety of compounds containing different amino- 

 acid groups, and substances of this kind, derived from 

 glycine and leucine, and from glycine and alanine, have 

 already been prepared. It seems' probable that by their 

 extended use compounds of the order of complexity of the 

 peptones or albumoses may soon be prepared. The appli- 

 cation of both methods is, indeed, still in its infancy, but 

 we can have little doubt that the genius which laid bare 

 the innermost secrets of the sugars will succeed in solving 

 many of the problems which surround the chemistry of the 

 albumins. Arthur Harden. 



T//E ANTARCTIC EXPEDITIONS. 



'T'HE report of Captain Scott to the presidents of the 

 Royal and Royal Geographical Societies, which is 

 printed in the July number of the Geographical Journal, 

 adds a number of points of geographical interest to those 

 previously published, especially with regard to the great 

 southern ice-barrier, and the nature of the lands discovered 

 by the British expedition ; while the map published at the 

 same time, which has had the advantage of revision by 

 Lieut. Shackleton since that officer's arrival, permits the 

 details of the narrative to be followed with much clearness, 

 although it is still to be considered merely provisional. 



The voyage down the east coast of Victoria Land brought 

 to light some new features in the configuration of the 

 country. Thus, in about lat. 75° 30', an enormous floe of 

 the inland-ice was seen to descend into the sea and extend 

 for many miles to seaward, closely resembling the Great 

 Barrier and the barrier formation which entirely fills Lady 

 Newnes Bay. Near the entrance to MacMurdo Strait 

 (between Erebus and Terror Island and the mainland), ice- 

 cliffs, 150 feet high, were again skirted, being evidently 

 the seaward face of the great glacier subsequently explored 

 by Lieut. Armitage. During the voyage eastward along 

 the face of the Great Barrier, soundings for some time 

 showed depths of more than 300 fathoms, the barrier edge 

 being very irregular, and varying from 30 to 215 feet in 

 height. In the neighbourhood of the eastern land dis- 

 covered by the expedition (King Edward VII. Land) the 

 soundings suddenly became less, varying from 70 to 100 

 fathoms. The bare patches seen among the snow slopes 

 of the new land, which are evidently the sharp spurs of 

 snow-capped hills, stand at a height of 2000 to 3000 feet. 

 The balloon ascent and sledge expedition made in long. 

 196° 15', showed that the surface of the barrier ' undulated 

 in long waves running W.S.W. and E.N.E. It was noticed 

 that here the ship neither rose nor fell in relation to the 

 ice, thus apparently indicating that the latter is floating. 



The winter quarters were established in February, and 

 the magnetic observatory was in readiness for the term- 

 day observations of March i, all the subsequent term days 

 being kept by Mr. Bernacchi without a break. On May 3 

 a strong southerly gale brought the first heavy snowfall, also 

 blowing the strait clear of ice to within 200 yards of the 

 ship. Mr. Hodgson was constantly engaged on his bio- 

 logical work, keeping holes open for his nets and fish- 

 traps, and all the officers assisted Lieut. Royds in the night 

 meteorological observations. Auroral displays were in- 

 frequent and feeble, but were carefully observed. The 

 winter sledge reconnaissances revealed much of the topo- 

 graphy of the neighbourhood, both on the south side of 

 Erebus and Terror Island, and between it and the main- 

 land, where there are three smaller islands, named White, 



1 The whole southern ice-sheet is spoken of throughout as the "barrier,' 

 though this term wotild more naturally apply to its northern face only. 



