Stress sensitive glucose oxidase-nylon membrane

Summary Glucose oxidase (GOD) was immobilized on a nylon membrane. No activity of the GOD-nylon membrane was observed under normal conditions but it appeared when the membrane was mechanically stretched. A linear relationship was observed between the stress strength and the GOD activity of the membrane. The appearance of the GOD activity of the membrane with stress was reproducible and the membrane could be stored for at least 2 months. Therefore, the GOD-nylon membrane can be called a stress sensitive membrane.     

A photochemical fuel cell system using Anabaena N-7363

Summary A blue-green algae, Anabaena N-7363, was immobilized in 2% agar gel. The hydrogen productivity of the immobilized algae was three times higher than that of free algae. The maximum hydrogen production rate by the immobilized blue-green algae was 0.52 moles h^–1 g^–1 (of wet gel) in the medium without nitrogen sources under illumination (10,000 lux). The oxygen evolved was then removed by a reactor containing aerobic bacteria. A photo-current of 15–20 mA was continuously produced for 7 days by the photochemical fuel cell system consisting of the immobilized Anabaena reactor, the oxygen-removing reactor and the hydrogen-oxygen fuel cell. The conversion ratio of hydrogen to current was from 80% to 100%.     

Synthesis of desmosterol and epidesmosterol from hyodeoxycholic acid

A new synthesis of desmosterol was described using hyodeoxycholic acid (3,6-dihydroxy-5β-cholanic acid) as a starting material. Epidesmosterol (3-hydroxycholesta-5,24-diene) was also synthesized for the first time from the same starting material.     

Electric field control of lipase membrane activity

Lipase (EC 3.1.1.3., from Pseudomonas sp.) was entrapped in collagen membrane containing liquid crystal (4-methoxybenzilidene-4′-n-butylaniline). The activity of the lipase–liquid crystal membrane at an applied voltage of 4 V was 3.4 compared to a membrane tested without imposition of an external electric field. A linear relationship was observed between the activity of the lipase–liquid crystal membrane and the current. The apparent Michaelis constant (K′_m) of the lipase–liquid crystal membrane under electric field was identical to that of the membrane under ordinary condition. Activation of the lipase–liquid crystal membrane was observed repeatedly, i.e., activation in the presence of an electric field and reversion to a basal level upon removal of the field occurred cyclically. Activity control of immobilized enzymes is desirable for switching devices of a bioreactor. Possible mechanisms of the lipase activation by electric field are discussed.     

Occurrence and induction of spermidine-N1-acetyltransferase in Escherichia coli

Spermidine acetylase activity was detected in extracts prepared from $\text{Escherichia coli}$ and there was a marked increase in activity over the early period of growth. This increase reached a maximum 3 h after inoculation and was followed by an increase in ornithine decarboxylase activity. The acetylase was also able to use spermine as a substrate, but not putrescine. With spermidine and acetyl-CoA as substrate, the product formed was exclusively N¹-acetyl-spermidine. This is the first evidence for the occurrence in bacteria of spermidine-N¹-acetyltransferase, an enzyme which has previously been described in mammalian cells. These results suggest that acetylation of spermidine may be involved in the growth of $\text{Escherichia coli}$ and in the regulation of its polyamine content.     

Controlling mechanism of ATP regeneration by glycolytic pathway in a yeast: Hansenula jadinii

Summary The regulatory mechanism of ATP regeneration by the glycolytic pathway in Hansenula jadinii cells was investigated by analyzing the initial stage of CDP-choline fermentation. As a result, the on-off of ATP regeneration was found to be determined by the ATP concentration overcoming the inhibitory effect of phosphate buffer on hexokinase activity. The concentration of ATP at the initial stage of fermentation was greatly influenced by the kinds and amounts of glycogen in cells. Based on these results, the regulatory mechanism of ATP regeneration by the glycolytic pathway is discussed in detail.     

Structure and function of the major tail protein of bacteriophage lambda: Mutants having small major tail protein molecules in their virion

Viable mutants of bacteriophage lambda having small major tail protein molecules in their virion have been isolated as pseudo-revertants of a defective prophage mutant (defK244) in gene V, which codes for the major tail protein. According to deletion mapping, the defK244 mutation is located near the translation terminal of gene V, whereas some mappable reversion mutations leading to small major tail protein molecules map upstream to defK244 but still downstream to all the amber mutations tested. This suggests (if not proves) that the removable part is located at or near the carboxyl terminal of the major tail protein. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis and buoyant density measurements of the mutant phage particles show that as much as one-third of the major tail protein molecule can be removed without losing its capacity to maintain the total shape and infectivity of the phage particles. In the three-dimensional structure of the tail the removable part of the molecule exists as a protrusion at the outer part of the tail tube according to electron microscopy and hydrodynamic calculations based on sedimentation velocity experiments.