Preparation and properties of bacterial chromatophores entrapped in polyacrylamide

Immobilization of fumarase by entrapment of rat liver mitochondria in polyacrylamide gel using gamma rays

A stable immobilized preparation of fumarase (EC 4.2.1.2) was obtained by entrapment of rat liver mitochondria in acrylamide polymerized by using gamma irradiation (100 kR). The enhanced stability and the efficiency of the entrapped enzyme have shown potential for repeated use for the production of L-malic acid from fumaric acid. The possible formation of succinic acid in the system could be controlled by incorporating malonate along with detergents such as sodium deoxycholate or sodium dodecylsulfate in the reactor system.

Modification by immobilization of the microenvironment of chromatophores of Rhodopseudomonas capsulata. The influence on light-induced ADP phosphorylation coupled to cyclic electron transport

Rhodopseudomonas capsulata chromatophores were immobilized with a co-crosslinking method. Immobilization was used as a tool for a defined modification of the chromatophore environment to study ATP production over a long period of time. The light-induced phosphorylation of ADP as a function of time was studied with chromatophores under different conditions: (a) native chromatophores with and without the hexokinase ATP-trapping system; (b) immobilized chromatophores without hexokinase, with the enzyme added in the bulk solution and with the enzyme co-immobilized in the matrix. The overall amount of ATP produced as a function of ADP concentration was studied for native and immobilized chromatophores. The global phosphorylation performed was also studied as a function of the amount of biological material used. The results can be explained by an effect of the ATP/ADP ratio. The results given by the immobilization show that the important point is not the ATP/ADP ratio in the bulk solution but the ratio value in the microenvironment of the chromatophore itself.

Stabilization of biological photosystems : immobilization of thylakoids and chromatophores for hydrogen production and ATP regeneration

Lettuce thylakoïds were immobilized by the action of glutaraldehyde at subzero temperature in the presence of albumin. Foam structures with good mechanical properties were obtained. The activity yields for photosystem II and photosystems I + II were found equal to 71 per cent and 35 per cent respectively. The yield for ATP regeneration from ADP and Pi was 26 per cent. Increases of stability after immobilization were observed for all the functions of thylakoïds when stored and when continuously working. Spheroplasts and chromatophores from Rhodopseudomonas capsulata were immobilized with the same method; yields for ATP regeneration were found equal to 40 per cent and 70 per cent, respectively. An important increase of stability after immobilization was observed in both cases.

Immobilized organelles and whole cells into protein foam structures: scanning and transmission electron microscope observations

Protein foam structures bearing cells and organelles were produced by using a co-crosslinking method with serum albumin and glutaraldehyde at sub-zero temperature. Morphological observations obtained with scanning and transmission electron microscopy indicate macroporous and homogeneous structures. The glutaraldehyde concentration was varied to reveal its effect on immobilized red cells. It was observed that the structural appearance of preatreated cells or subcellular fractions (thylakoids from lettuce ; spheroplasts and chromatophores from R. capsulata) is preserved during the immobilization process. The morphological features of foam particles are always related to the observed kinetic activities of the specimens.

Adenylate kinase from Rhodospirillum rubrum

A partial purification and some properties of adenylate kinase from the photosynthetic bacterium Rhodospirillum rubrum are described.

Immobilization of yeast microbodies by inclusion with photo-crosslinkable resins

Yeast microbodies containing FAD-dependent alcohol oxidase, catalase and D-amino acid oxidase were isolated from methanol-grown cells of Kloeckera sp. 2201 and immobilized intact in matrices formed by a short-time illumination of photo-crosslinkable resin oligomers. The relative activities of catalase, alcohol oxidase and D-amino acid oxidase of the gel-entrapped microbodies were 36, 76 and 31% respectively as compared with those of free microbodies. Immobilization enhance d the stability of catalase to a certain degree, but not that of alcohol oxidase. The pH/activity profiles of catalase and alcohol oxidase of the entrapped organelles showed more narrow pH optima than those of the free counterparts. D-Amino acid oxidase in immobilized microbodies showed a somewhat higher Km value for D-alanine than that in free ones. Immobilized microbodies oxidized two moles of methanol to form two moles of formaldehyde with consumption of one mole of molecular oxygen. Addition of 3-amino-1,2,4-triazole, an inhibitor of catalase, reduced the formation of formaldehyde to half the amount without change in the amount of oxygen consumed, indicating the synergic action of alcohol oxidase and catalase in methanol oxidation in the microbodies of living yeast cells.