The reaction of nitrite with the haemocyanin of the Roman snail (Helix pomatia).

The reaction of nitrite at pH 5.0-7.0 with the deoxyhaemocyanin of a mollusc, the Roman snail (Helix pomatia), yielded nitrosylhaemocyanin (CuIA.

The reaction of nitrogen monoxide with the haemocyanins of the crayfish Astacus leptodactylus and the snail Helix pomatia.

The rate of the reaction of Astacus leptodactylus methaemocyanin with NO follows the Henderson-Hasselbalch equation with a pKa of 5.85, suggesting that one imidazole ligand of Cu was exchanged for NO. The reaction is blocked by F- as a bridging ligand.

The reaction of hydroxyurea with oxyhaemocyanin and methaemocyanin of the crayfish Astacus leptodactylus and the snail Helix pomatia.

The reaction of hydroxyurea with the oxyhaemocyanins of Astacus leptodactylus and Helix pomatia yielded methaemocyanins which could be regenerated with hydroxylamine. Hydroxyurea did not react with Astacus methaemocyanin, but quantitatively regenerated Helix methaemocyanin under N2. The reaction of hydroxyurea with Helix haemocyanin at pH 5.

The reaction of nitrite with the haemocyanin of Astacus leptodactylus.

The reaction of nitrite at pH 5.7 with deoxyhaemocyanin of Astacus leptodactylus yielded methaemocyanin in two one-electron steps, as nitrite was reduced to NO. This methaemocyanin could be almost fully regenerated by an anaerobic treatment with HONH2, in contrast with the methaemocyanin prepared with H2O2.

Selective absorption and scattering of light by solutions of macromolecules and by particulate suspensions.

For particulate suspensions and for solutions that scatter light measurably the total absorbance A generally contains contributions due to specific absorption (Aa) and scattering of light (As). The quantity As is closely related to the turbidity tau. In general, spectrophotometry of such systems requires proper modification of the spectrophotometer used in order to permit accurate determination of the absorbance A and of the derived quantities Aa and As.