Tryptic action across a membrane.

Tryptic action occurs when a layer of bovine serum albumin adsorbed on a nickel-plated slide and protected by a Formvar membrane 120 A thick is treated with dilute trypsin solution. But experimental evidence indicates that the trypsin molecules to not cross the membrane. Thus the proposal that trypsin can exert its enzymatic action without intimate contact with the substrate, first set forth in 1948 but later abandoned in favor of a "forced diffusion" hypothesis, now appears the correct interpretation.

Daily periodicity in the activity of a slide used to perform immunologic reactions at a liquid-solid interface.

Nickel-plated slides were prepared by evaporating a nickel layer (congruent to 4000 A thick) on glass slides in the presence of a magnetic field whose lines of force were perpendicular to the surface of the slides. Such slides are called active. After being coated with a layer of bovine albumin, they could absorb a layer of antibodies 70-80 A thick.

A 24-hour periodicity in the activity of a nickel-coated glass slide used for carrying out immunologic reactions at a liquid-solid interface.

Active nickel-plated slides are prepared by evaporating the metal in the presence of a magnetic field oriented perpendicularly to the slide, the surface being metallized facing the south pole of the field. Active slides coated with an antigen layer (bovine albumin or ovalbumin) can specifically adsorb a layer of antibodies nearly twice as thick (70 to 80 A) as that adsorbed on inactive slides (40 A). The activity of a slide varies within a 24-hour period.