Effects of nicotinamide, isonicotinic acid hydrazide, and 3-acetylpyridine on the growth and nicotinamide abenine dinucleo-tide content of L cells

1. Addition of nicotinamide (l0-2M) into the culture medium brings about an increase of the NAD content and the inhibition of the growth of L cells in culture. This rise of NAD brought about by nicotinamide lasts for 2 to 3 days, and thereafter gradually subsiding, it returns to normal level. 2. When L cells are cultured for several days in the same medium without addition of nicotinamide, there occurs a slow-down of mitosis with lapse of cultivation time but it has been found that this is in no way connected with the intracellular content of NAD. 3. By the addition of isonicotinic acid hydrazide (l0-2M) into the culture medium, there can be recognized a decrease of NAD content in L cell and the inhibition of cell growth. 4. In the case when 3-acetylpyridine (l0-2M) is added, a decrease of intracellular content of NAD in L cells and a marked inhibition of the cell growth can be observed. In the groups cultured in the media, containing 3-AP at the concentration of l0-3M or l0-4M can be seen neither inhibition nor acceleration of the cell growth. The oxygen uptake of the cells cultured in the medium containing 3-AP (l0-2M) hardly differs from that of the control group cultured in the medium not containing 3-AP. 5. On the basis of these results discussion has been made on the relation ship between mitosis and NAD content in the cell.</p

Fine structure and biochemical properties of purified cytochrome oxidase

For the purpose to reveal the correlation between molecular structure and biochemical functions of cytochrome oxidase the author studied purified cytochrome oxidase by using high resolution electron microscope and biochemical methods. 1. Cytochrome oxidase was purified from the cytochrome oxidase-rich submitochondrial membrane (green membrane), obtained from beef heart mitochondria, by three different methods; modification of the method of OKUNUKI et ai., method of FOWLER et ai. and modification of the method ofJACOBS et ai. All the preparations showed a high specific activity under appropriate conditions and consisted mainly of small particles measuring approximately 80 to 90 A. in diameter. 2. The particle, measuring approximately 80 to 90 A. in diameter, took a cylindrical form measuring about 70 A. in diameter at the base and 95 A. in height in an appropriate condition. Many experimental results indicate that the particle is the smallest, fundamental unit of the active cytochrome oxidase. For this reason it was designated as the unit particle of cytochrome oxidase (abbreviated as UPCO). 3. The molecular weight of the unit particle, calculated from its volume and average density (1.24) of lipoproteins (3: 7), was about 270,000. The value was roughly twice the minimum molecular weight of 128, 000 calculated from the heme a content. Accordingly, it is considered that the unit particle contains two heme a molecule and two copper atoms. 4. It was suggested electron microscopically that the particle collected in the 22.6 S position by sucrose gradient ultracentrifugal analysis was a dimer of the unit particle of cytochrome oxidase and also that the particle collected in the 5. 7 S position was a half of the unit particle of cytochrome oxidase. 5. It was also suggested that the particle observed on the green membrane was a subunit of cytochrome oxidase, containing one heme a and one copper atom, and the unit particle of cytochrome oxidase was constituted of two of the particles observed on the green membrane. Namely, the results indicate that the molecular state of cytochrome oxidase on the green membrane apparently differs from that of the purified cytochrome oxidase.</p

Cytochrome oxidase in a cytochrome oxidaserich submitochondrial membrane

1. A cytochrome oxidase-rich submitochondrial membrane (green membrane) was obtained from beef heart mitochondria after extraction of flavoproteins, cytochrome b, Cll C, etc. by treating with deoxycholate and potassium chloride. 2. The green membrane was formed by self assembly from the membrane fragments (flat sheets), which derived from the cristae membrane of mitochondria and had essentially the same particulate structure as the green membrane. 3. The green membrane exhibited regular arrays of small particles on the surface, measuring approximately 50 to 60 A in diameter with center to center distance of about 70 A. These particles sometime were arranged in a woven structure on the surface. 4. Both the configuration of the particles and the regularity of the arrangement were influenced by detergents and temperature. 5. Green membranes as well as beef heart mitochondria and electron transfer particles commonly retained membrane-structure after sonication and exhibited higher specific activity of cytochrome oxidase than that of purified cytochrome oxidase, if the activity is calculated on the basis of heme a concentration (sec1 / 10 m,lJ.moles of heme a/3 ml). The results suggest that the active sites of cytochrome oxidase are arranged on the surface of these membranes. 6. From these results and other experimental findings, an intimate correlation between cytochrome oxidase and the particles observed on the green membranes is suggested.</p

Isolation of oligomycin-sensitive adenosine triphosphatase from beef heart mitochondria and analysis of its fine structure

1. An oligomycin -sensitive ATPase was isolated and partially purified from beef heart mitochondria. The specific activity of ATPase sensitive to oligomycin of the fraction was five to eight times that of aged mitochondrial or of DNP-induced mitochondrial ATPase assayed under the same condition. 2. Electron micrographs of the partially purified oligomycin- sensitive ATPase reveal a structure in which headpieces are regularly attached by way of stalks to a thread-like structure derived from a superficial portion of base pieces. 3. A high concentration of the structured material coincided with a high activity of oligomycin-sensitive ATPase. When the headpieces were detached from the structure, the ATPase became insensitive to oligomycin. 4. The fraction of oligomycin -sensitive ATPase was essentially free of membrane structure and was contaminated with a small amount of cytochromes b and Cl but no cyt. a. Cytochrome concentrations of the preparations were indifferent to the activity of oligomycin sensitive ATPase. It follows that ATPase does not require cytochromes or membrane structure for its oligomycin sensitivity. 5. From these results it seems that the factor rendering ATPase sensitive to oligomycin should be contained in the stalks and/or the thread-like portion of basepieces of the structure. The structure is the simplest unit of oligomycinsensitive ATPase as yet obtained. 6. The structure was called &#34;oligomycin-sensitive ATPase particles&#34; (abbreviated as OSA particles). A unit of OSA particles consists of a headpiece attached by a stalk to a portion of base piece.</p

Electron microscopic observation of mitochondrial DNA isolated from a human kidney: circular dimers in histologically normal organ mitochondria

Circular DNA isolated from human kidney mitochondria was studied by electron microscopy. I. Mean contour length of monomers of the mitochondrial DNA was 4.96 ± SE 0.28 /&#956; 2. The complex molecules (oligomers) of mitochondrial DNA were observed in frequency of 6.2 per cent. Among them circular dimers accounted for two per cent of all circular DNA molecules. 3. Circular DNA fibers with an intermediate perimeter between the&#12288;monomer and dimer, and with a contour length shorter than 3 &#956; were occasionally observed. 4. Some discussions were made on the emergence of the circular dimer.</p

New methods for the histochemical and cytochemical demonstrtion of cytochrome c oxidase and of cytochrome c- cytochrome oxidase system

New histochemical and cytochemical methods for the demonstration of cytochrome c oxidase and of cytochrome c-cytochrome oxidase system are described, using neotetrazolium chloride in the presence of p phenylenediamine with or without additional cytochrome c. These enable the cytochemical visualization of the sites of enzyme activity at the intracellular level in fresh cell suspensions and in fresh tissue blocks under aerobic conditions, and permit the histochemical visualization of the distribution of the enzyme activity in various tissues in frozen tissue sections. The colorimetric estimation of the enzyme activity is also possible in the combination of the methods previously described.</p

Flavin and cytochrome contents in the mitochondria of the heart and liver

With a certain fixed methods of analyses, we carried out the determination of flavins and cytochromes in the mitochondria (Mt) and electron transfer particles (ETP) of the heart and liver of rats and cows, and made a comparison of the data with one another. Our findings may briefly be summarized as follows. 1. The concentration of each component of the beef heart mitochondria proved to be 0.47 for acid extractable flavins; 0.22 for acid nonextractable flavin; O. 75 for cytochrome (cyt.) a; 0.58 for cyt. b; and O. 51 for cyt. C + Cl, all units being m&#956; mole per mg of protein. 2. In the beef liver mitochondria it was 0.46 for acid extractable flavins; 0.18 for acid non-extractable flavin; 0.092 for cyt. a; 0.089 for cyt. b; and 0.122 for cyt. C+Cll likewise all units in term of m&#956; mole per mg of protein. 3. In the case of rat heart mitochondria, it was found to be O. 42 for acid extractable flavins; 0.22 for acid non-extractable flavin; 0.88 for cyt. a; 0.41 for cyt. b; and 0.62 for cyt. C + Cll all in m&#956; mole per mg of protein. 4. In the rat liver mitochondria it was 0.56 for acid extractable flavins; 0.19 for acid non-extractable flavin; 0.20 for cyt. a; 0.14 for cyt. b; and 0.19 for cyt. C+Cl. 5. The concentration ratios of Fs, cyt. a and cyt. b of the mitochondria, what are considered to be intrinsic and fixed components of the mitochondrion. to those of the electron transfer particles were 1. 3 in both the beef heart and the rat heart, while 2.2 in the beef liver and 2.1 in the rat liver. 6. These findings were compared with the data reported by other workers, and also a discussion was made on the molecular organization of the mitochondrial inner membrane.</p