PRODUCTS OF HYDROLYSIS 



69 



two-thirds of its sulphur, as does free cystine, many of the proteins in 

 the preceding table appear to contain a relatively large proportion of 

 sulphur in some other complex than cystine. The following table 

 shows the amount of cystine sulphur calculated on the above assump- 

 tion and the amount of sulphur unaccounted for : 



For many of these proteins the quantity of sulphur thus unaccounted 

 for is relatively large, and this makes it probable that many proteins 

 contain sulphur in some other combination than cystine. 



If the generally uniform physical properties of all these proteins is 

 considered as well as their similar relations toward extremely small 

 quantities of base and acid, it seems more probable that they have 

 similar high molecular weights and contain different numbers of sulphur 

 atoms than that, as has frequently been assumed, they each contain 

 two sulphur atoms and have correspondingly different molecular 

 weights. Six of these twenty-one proteins contain approximately 0-4 

 per cent, of sulphur and must therefore have molecular weights of at 

 least 15,000. If the empirical formulas and molecular weights which 

 correspond most nearly to 15,000 are calculated for these proteins on 

 the assumption of a definite number of sulphur atoms, the following 

 results are obtained : 



