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1. The "oxygenated" form of cytochrome oxidase has been generated by treatment of the enzyme with ascorbic acid.2. "Oxygenated oxidase" so generated is stable over long periods (24 h).3. Sedimentation velocity experiments have shown the "oxygenated oxidase to be a less compact molecule than the oxidized.

A simple, practical calculation procedure has been developed for predicting the changes in molecular weight distribution of a polymer undergoing random crosslinking and/or degradation. Simulations of the random crosslinking and degradation of narrow and broad Poisson-type distributions have been made. The results agree with those calculated from Kimura's analytical solutions to Saito's general equations after a correction has been made for a mathematical error in Kimura's solution. This method can be applied to determining the probabilities of crosslinking and scission for any arbitrary molecular weight distribution expressed in tabular form. The importance of using narrow distribution samples to estimate crosslinking from changes in molecular weight distribution is graphically demonstrated.

The total collision cross section has been measured for argon atoms, with energies between 300 and 1100 electron volts, scattered in room temperature argon. In the region between 700 and 1000 volts, the cross section shows a maximum indicative of inelastic scattering, probably due to ionization by the high energy atoms.The repulsive potential between two argon atoms has been evaluated from elastic collision cross sections (deduced from observed values of the total collision cross section) using a method which takes account of the greater probability of small angle scattering by averaging the cross section over the length of the scattering path. The results may be expressed by V(r)=4.61×10−11/r4.33 ergs or V(r)=3.66×10−8 exp(−6.88r12) ergs for values of r between 1.37 and 1.84A.

A procedure is outlined by which sedimentation analyses of small quantities of mucin glycoproteins can be performed. Rat intestinal goblet cell mucin was stained with periodic acid-Schiff reagent to permit detection by light absorption at 555 nm. PAS treatment resulted in chemical modification of sialic acid and 55% of fucose residues in the mucin. No other chemical or physical alterations were detected. The stained mucus was subjected to band ultracentrifugation using D2O-containing solvents. Sedimentation was monitored by scanning at 555 nm. Results compared favorably with those reported earlier for conventional boundary ultracentrifugation of intact goblet cell mucin. Because of the low concentrations of mucin used in band ultracentrifugation (0.2–1.5 μg protein/ml), S20,w values are comparable to sedimentation coefficients at zero concentration (So values), determined by conventional means.

Single component guinea pig insulin was found by sedimentation equilibrium centrifugation to exist in neutral solution as a monomeric species only, even in the presence of zinc ion. This insulin, in contrast to bovine insulin, did not bind zinc ion at pH 7.4. The biological activity of guinea pig insulin, estimated by mouse convulsion assay, was 2.14 I. U. per mg.