Surface Films of Gliadin

MITCHELL1 has reported that under suitable conditions proteins can be spread from a solution to give films the force-area curves of which show a sharp transition point in the region of 1–2 dynes/cm., the extrapolated areas of the two distinct portions of the curve being approximately 0.3 and 0.7 × 10−7gm. /sq. cm. respectively. The requirements for such a curve seem to be (1) a dilute spreading solution, and (2) a time interval of 1–15 hours between spreading and measurement. Since this is the first case in which a definite transition point has been observed with proteins, we have repeated the measurements using, so far as could be ascertained, the same conditions as Mitchell. Dilute solutions of gliadin in 70 per cent aqueous alcohol were used for spreading on N/100 sulphuric acid or hydrochloric acid substrates, and the time interval ranged from 3 to 1,065 minutes.