[Cow's milk alkaline phospharase. II. Subunit structure, metalloproteic nature and kinetic parameters (author's transl)]. / Phosphatase alcaline du lait de vache. II. Structure sous-unitaire, nature métalloprotéique et paramètres cinétiques

Alkaline phosphatase (EC 3.1.3.1) from cow's milk as a dimer comprising two identical or very similar subunits of about 85 000 molecular weight. The enzyme contains 4.9 +/- 0.6 gatoms of zinc per mol of protein. The essential kinetic properties are the same as those of other alkaline phosphatases: variation of pH optimum value, the lack of specificity, increase of Km and V with pH value. The phosphotransferase activity is enlarged, at constant concentration of acceptor, with an increasing concentration of donor. The small size of molecules and the presence of hydroxyls and amino groups increase the percentage of transfer phosphate. The phosphotransferase reaction is better with the D-isomer of serine and the enzyme possesses a more important affinity for the D-phosphoserine.

Cow kappa-casein: structure of the carbohydrate portion.

The detailed sugar sequences of the two main carbohydrate portions of cow kappa-casein were established by enzymic and chemical methods and by mass spectrometry. The sugar sequences correspond to widespread sugar parts occurring in many glycoproteins.

[Influence of hydrothermic and enzymatic treatments on the nutritive value of Faba beans: in vitro study]. / Influence des traitements hydrothermiques et enzymatiques sur la valeur nutritionnelle des proteines de féveroles : étude par méthodes in vitro.

In order to improve the digestibility of the Faba bean flour an hydrothermic enzymic and fermentation treatment has been thought out (US patent 395 8015, Ets Ury, M. Gay). This study aims at stemming out the nutritionnal and structural repercusions of this treatment on the Faba proteins. The nitrogen distribution is deeply changed : total nitrogen increase (47%), water soluble nitrogen decrease (41%), water soluble non-protein nitrogen increase. The treatment can enrich the flour in nitrogen but the proteins supplement is insoluble in water. The treatment changed the electrophoretic behaviour of flour proteins letting disappear precipitable pH 4,5 proteins. Amino acid composition is slightly changed, however there is an increase of lysine and methionine (15 et 25%) and a decrease of cysteine (28%). The chemical score shows sulfur amino acids and tryptophan deficiency. Enzymatic (pepsine and pancreatine mixture) liberation of all amino acids is low and is not improved by the treatment but for the lysine. Cell proteins supplement, which appeared during the treatment (61%), water insoluble, could improve nutritive value of the flour if a more complete destruction of the cell walls permitted their liberation and their solubilization.

[Ultra-flash sterilization of fluid food by friction]. / La stérilisation ultra-rapide par friction des aliments liquides.

The ATAD process without heat exchange nor steam mixing allows the sterilization in a very short time. With milk, the sterility has been attained regularly at 140 degrees C/0,54 seconds. Only small changes occurred in nitrogen distribution. An homogeneizing effect upon fat emulsion is noticeable. The amino-acid composition of isoelectric fraction is not that of casein owing to the coprecipitation of a part of whey protein at pH 4,6, but they do not reveal any degradation. The enzymatic digestion of proteins (pepsin + Pancreatin) is a little improved by this treatment; the availability of lysine, measured by dinitrophenylation or guanidination, is hardly modified. All the blocked forms of lysine (Maillard reaction, lysino-alanine reaction, peptidoïd boundings) occurs only under more drastic conditions. The beta-lactoglobulin-kappa-casein complex formation slightly hampers the enzymatic clotting of sterilized milk. The forms of calcium are not seriously disturbed and such a milk is suitable for cheesemaking; we can obtain cheese with very few non-lactic bacteria.

[Denaturation and enzymatic proteolysis in vitro of protein fractions of soya flour]. / Dénaturation et protéolyse enzymatique in vitro de fractions protéiques de la farine de soja

Soya, in spite of its high nutritional value and moderate cost, possesses certain undesirable qualities which limit its use in animal and human nutrition. The amendment of these qualities has resulted in much work. In this study the effects of technological treatments on the properties of certain protein fractions capable of being produced industrially were observed. Three fractions were prepared from defatted soybean flour of the "Harosoy 63" variety: an acid-precipitated fraction, a cold-insoluble fraction at 0-3 degrees C, and a water-soluble fraction. The properties of the fractions were studied both before denaturation and after denaturation by either heat or alcohol. The degree of proteolysis of each fraction by two digestive enzymes, pepsin and trypsin, was measured by the increase of non-protein nitrogen as a function of time. Several methods were used for electrophoretic analysis. The results showed that the thermal treatment at 100 degrees C and the treatment with varying concentrations of ethanol (from 10 to 100 p. 100) modified electrophoretic diagrams and the solubility of the proteins in trichloracetic acid. Moderate, moist heating of the protein fractions (100 degrees C, 20 mn) before proteolysis by pepsin and trypsin, in general, favored proteolysis. The most marked effect observed was in the acid-precipitated fraction (in which Kunitz inhibitor was concentrated treated by trypsin. Heating the fractions beyond thirty minutes had a negative effect on proteolysis: the level of proteolysis was the same, or in some cases, lower than before denaturation, especially on subsequent treatment with pepsin. The effects of the ethanol treatment were different from that of heat: the proteolysis was accelerated only with the acid-precipitated fraction.

Study on the composition of casein from individual human milks.

The study of the chemical composition and of the electrophoretograms of 21 different human whole casein samples confirms the presence of an important heterogeneity between the different samples. A very considerable variability of phosphorus and sugars contents and a correlation between the different sugars components of the casein have been demonstrated statistically. The study of 3 milk samples from the same woman showed a decrease of the amino-sugars of the casein after the birth.

Localisation of the prosthetic sugar groups of bovine colostrum kappa-casein.

The study of glycopeptides obtained after enzymic digestions of bovine colostrum kappa-caseinoglycopeptide obtained 15 minutes after calving, demonstrated the presence of two prosthetic sugar groups linked to threonine residues, instead of only one and up to 10 in the case of bovine (normal) and human caseinoglycopeptides, respectively. The secondary structure of bovine kappa-caseinoglycopeptide was reinvestigated.

On binocular alternation.

Diaz-Caneja (1928) made some prescient observations about binocular rivalry. Being in French, however, his paper remained largely unknown to the broader research community. His findings are similar to those reported very recently by contemporary researchers who had independently observed similar phenomena. Using concentric circles and parallel lines as stimuli, Diaz-Caneja presented half of each form to opposite eyes to provoke binocular rivalry. He observed periods in the ensuing binocular alternations in which rivalry occurred between the good Gestalt forms, despite the fact that they were distributed between the eyes. He proposed that each half of a good form generates synchronised oscillations in the visual system, and that this synchronisation enables the dichoptically viewed halves of the one form to be perceived as a whole.