On the vitamin B6 requirement of exercise tomato roots grown in sterile culture.

The main purpose of this work was to determine whether ethanolamine is a precursor of vitamin B6 in the excised tomato root. The suggestion that this might be the case arose from the fact that ethanolamine replaces the vitamin in the nutrition of excised tomato roots grown in sterile culture (Boll, 1954). Analytical data presented by Boll (1959) were interpreted to mean that ethanolamine is not a precursor of vitamin B6 in the excised tomato root. However, it became necessary to reexamine this question because of some recent work by Morris and Woods (1959), who reported that glycoladehyde (GA) gave good replacement for the vitamin in the nutrition of a vitamin B6 requiring mutant of Escherichia coli. According to several authors (Fruton and Simmonds, 1958), ethanolamine is converted to GA metabolically

Metabolism of C14-serine, C14-ethanolamine and nitrogen containing phosphatides in relation to the nutritional requirement of excised tomato roots for vitamin B6.

Ethanolamine was shown to replace vitamin B6 in the nutrition of excised tomato roots grown in sterile culture (Boll, 1954a, 1959a). This replacement cannot be explained as a precursor effect (Boll, 1954a; Nillernot, 1962). An alternative explanation of the replacement was made by Boll (1954a, 1959a). The explanation involved negative feedback control, by ethanolamine, of a postulated serine decarboxylase yielding ethanolamine, and requiring pyridoxal phosphate as coenzyme. In this way, ethanolsmine would exert a sparing action on the limited amount of vitamin B6 which, as shown by Boll (1954a), is synthesized by the roots. [...

Etude et amélioration de la chromatographie en lit expansé

La chromatographie en lit expansé est une technique primaire de purification des protéines qui permet de combiner clarification, concentration et purification en injectant directement le moût de fermentation dans la colonne, par un flux ascendant. Dans un premier temps, une nouvelle colonne de chromatographie en lit expansé avec un distributeur de flux conique a été conçue afin d'améliorer la qualité de l'écoulement et d'éviter la présence d'une grille, pour limiter les problèmes de colmatage à forte concentration cellulaire. Cette colonne offre alors de meilleures performances comparées aux colonnes actuellement commercialisées. Dans un second temps, une étude physico-chimique des interactions entre les billes adsorbantes et les levures S. cerevisiae a montré l'importance de se placer dans les conditions réelles de l'expérience et de prendre en compte l'hydrodynamique et l'ensemble des interactions électrostatiques et non électrostatiques pour décrire le mécanisme des interactions. Enfin, la lipase de Yarrowia lipolytica a été purifiée par cette technique dans la colonne à distributeur conique, avec un rendement de 98,8% et un facteur de purification de 3,55, directement en sortie de fermenteurExpanded bed adsorption (EBA) is a primary recovery technology allowing the adsorption of target proteins from unclarified feedstock, by an increase in bed voidage, combining separation, concentration and purification steps. First, a new column with a conical distributor has been specially designed to avoid any grid and limit problems of clogging with high cellular concentration culture broth. This column gives a better efficiency compared with commercial ones. Second, a physico-chemical study of the interaction between adsorbent beads and the yeast S.cerevisiae demonstrated the importance of considering the real working conditions, integrating the hydrodynamics and all kind of interactions (electrostatic, Lifshitz-van der Waals and polar interactions). Then, the lipase of Yarrowia lipolytica has been well purified by this technique using the new column with conical distributor, directly from unclarified feedstock. The yield reached 98.8% and the purification factor approached 3.55TOULOUSE-INSA (315552106) / SudocSudocFranceF