Raphaël Witters

Human urinary protein 1: evidence for identity with the Clara cell protein and occurrence in respiratory tract and urogenital secretions.

Protein 1 (P1), a low mol mass urinary protein of unknown function, has been purified, sequenced and quantified in human biological fluids. The molecular size, subunit composition and partial amino acid sequence of P1 are similar to those of the 10 kDa Clara cell protein (CC10), a lung secretory protein. P1 is found in high concentrations in sputum, bronchoalveolar lavages, urine and semen of healthy individuals and in urine of some pregnant women. Contrary to what is claimed, P1 or CC10 is not a specific and unique product of the lung, but like its homologue in rabbits (uteroglobulin) it is also present in urogenital secretions. P1 or CC10 may act as a natural immunosuppressor protecting the respiratory and urogenital tracts from unwanted inflammatory reactions.

The formation of Helix pomatia methaemocyanin accelerated by azide and fluoride

Haemocyanin, the oxygen-carrying pigment from the haemolymph of the mollusc Helix pornaria, shows two copper-oxygen absorption bands with a maximum at 346 and at 580 nm. These bands decrease slowly on storage [ I] . They reach about half their original value in one year and can be regenerated with hydrogen peroxide [2) and with hydrogen suiphide [3]. A considerable decrease of the copper bands after a few weeks, observed in the separation of cyand phaemocyanin in the presence of 1 M NaCl at pH 5.7, incited us to investigate the influence of halogenides. Similarly the abnormal bleaching of the colour of fresh haemocyanin by the addition of 3 mM sodium azide as a preservative led us to try the action of azide (C. Gielens, unpublished observation).

The fast reduction of Helix pomatia methaemocyanin with hydrogen sulphide

Oxygen binds reversibly to the copper of Helix pomatia haemocyanin in a ratio of 1 O,/ 2 Cu, giving rise to absorption bands at 346 and 580 nm [ 11. These bands show a continuous decrease when haemocyanin solutions are stored in air over a period of months [2]. This ageing can be prevented by storage of haemocyanin under carbon monoxide [3 J . Aged haemocyanin preparations can be regenerated by treatment with hydrogen peroxide, cysteine [4] or hydroxylamine [5]. It was clearly demonstrated that the very slow regeneration with cysteine is mediated by hydrogen peroxide [6]. This paper reports the fast regeneration of aged haemocyanin by treatment with small amounts of sulphide.

A small-angle x-ray scattering study of the quaternary structure of the 24-S component of the hemocyanins of homarus vulgaris and cancer pagarus

Abstract The quaternary structure of the 24-S components of the hemocyranins of Homarus vulgaris and Cancer pagurus was studied by small-angle X-ray scattering in solution at neutral pH. Their scatterng curves are very similar and could be fitted by the theoretical scatterng curves based on a model similar to the one proposed earlier for the hemocyanin of Astacus leptodactylus (Pils, I., Goral, K., Hoylaerts, M., Witters, R. and Lontie, R. (1980) Eur. J. Biochem. 105, 539–543). The following molecular parameters were obtained: H. vulgaris hemocyanin, radius of gyration = 7.25 nm, radius of gyration of the cross-section = 3.9 nm, maximum dimension = 23.5 nm, maximum dimension of the cross-section = 11.4 nm, volume = 1620 nm 3 ; C. pagarus hemocyanin, radius of gyration = 7.10 nm, radius of gyration of the cross-section = 3.8 nm, maximum dimension = 23.0 nm, maximum dimension of the cross-section = 11.2 nm, volume = 1600 nm 3 .

The reaction of azide with Limulus polyphemus methaemocyanin

The oxyhaemocyanin of the arthropod-Limulus polyphemus showed no reaction with azide at pH 5.0, in contrast with the oxyhaemocyanin of the mollusc Helix pomatia, which yielded methaemocyanin [ 1]. By the action of stoicheiometric amounts of hydrogen peroxide on arthropodan deoxyhaemocyanin, methaemocyanin was readily obtained [2]. The results presented here show that the methaemocyanin of L. polyphemus with azide gives a reaction analogous to that of the molluscan methaemocyanin [3].

Reconstitution of Helix pomatia hemocyanin with cyanocuprate(I)

Abstract The possibility to reconstitute hemocyanin with copper(II) ions can be explained by the reduction of these ions by residual cyanide and by the formation of a stable copper(I) complex that introduces copper(I) into the active site of hemocyanin. The reconstitution of hemocyanin with cyanocuprate(I) in air is disturbed by a secondary reaction whereby the copper-oxygen band is destroyed irreversibly as a function of time. The formation of hydroxyl radicals at the active site of hemocyanin seems partially responsible for its destruction

The Reaction of Helix pomatia Methaemocyanin with Azide and Flouride

Haemocyanin, the copper protein of the haemolymph of Helix pomatia, reversibly binds oxygen in a ratio of 1 O2 per two copper atoms (Guillemet and Gosselin, 1932).

Binuclear Electron-Paramagnetic-Resonance Signals of Arthropodan Methaemocyanins in the Presence of Nitrite

The deoxy- and oxyderivatives of haemocyanin are diamagnetic; in the oxyderivative the copper(II) ions in the binuclear copper site are strongly magnetically coupled. A strong interaction between the two copper(II) ions in a copper pair is favoured when only very few atoms form a superexchange pathway leading to a coupling of the unpaired spins. The copper(II) ions can also be magnetically coupled as a function of their distance and thus give rise in electron paramagnetic resonance (EPR) to a broad triplet signal near g = 2 and a weakly allowed signal at half field near g = 4, as observed for Helix pomatia methaemocyanin with acetate at pH 5.7 (1, 2).