H. E. Woodman 239 



gliadines gave readings which fell on the racemisation curves which the 

 two proteins have been shown to possess in common. 



3. Vombining weights of the gliadines. 



Foreman (7) has shown that aqueous-alcohohc solutions of certain 

 amino-acids containing about 85 per cent, alcohol can be titrated accu- 

 rately with alkali in the presence of phenolphthalein. The amino groups 

 under these conditions display no basicity to phenolphthalein and the 

 carboxyl groups can therefore be estimated by titration. 



On the basis of this observation, it seemed probable that the basic 

 effect of the free amino groups in the ghadine molecule towards phenol- 

 phthalein might be held in abeyance when the protein was dissolved in 

 alcohol, thus permitting of the direct estimation of the free carboxyl 

 groups in the molecule by titration with alkali. Accordingly, 2 per cent. 

 solutions of the gliadines in 80 per cent, alcohol were titrated with 

 iV/10 NaOH in the presence of phenolphthalein, and the following results 

 were obtained : 



Manitoba flour gliadine 1 grm. dry, ash-free protein required 1-95 c.c. 



A7I0 NaOH. Combining weight = 5128. 

 Enghsh ,, „ 1 grm. dry, ash-free protein required 1-99 c.c. 



iV/10 NaOH. Combining weight = 5026. 

 It follows that both gliadines possess the same combining weight, the 

 difference recorded being due to experimental error. This fact affords 

 further confirmation of the identity of the gliadines. 



The data recorded above possess an additional interest when con- 

 sidered in conjunction with the minimum molecular weight ascribed to 

 gliadine by Osborne (8) on the assumption that the molecule contains 

 five atoms of sulphur, viz. 15560. It would thus appear probable that 

 the ghadine molecule contains three or a multiple of three free carboxyl 

 groups. 



Investi(!ation of the glutenine samples. 



1. Specific rotation in iV/25 NaOH. 



0-5 per cent, solutions of the glutenines in iV/25 NaOH were examined 

 by means of the polarimeter with the following results : 



Glutenine from Manitoba flour [a]^, = — 99-5°. 

 ., English „ [a]^, = - 78-8°. 



2. Similar differences in the optical properties of the glutenines were 

 observed during the racemisation of the proteins by means of iV/2 NaOH 

 at .37° C. 



Joum. of Agric. Sci. xn 17 



