Sonic oscillators

Liposomes (Fig. 8) are completely closed vesicular bilayer structures formed by exposing phosphoglycerides in water suspension to sonic oscil-... 

Hybridization measurements have been used in many studies of homology of nucleic acids from different species. A nucleic acid is cut (e.g., by sonic oscillation) into pieces of moderate length ( 1000 nucleotides) and is denatured. The denatured DNA fragments are mixed with denatured DNA of another species. Nucleotide sequences that are closely similar between species tend to hybridize, whereas sequences that are... 

Where within the mitochondria are specific enzymes localized One approach to this question is to see how easily the enzymes can be dissociated from mitochondria. Some enzymes come out readily under hypotonic conditions. Some are released only upon sonic oscillation, suggesting that they are inside the matrix space. Others, including the cytochromes and the flavoproteins that act upon succinate and NADH, are so firmly embedded in the inner mitochondrial membranes that they can be dissociated only through the use of non-denaturing detergents. 

However, they do transport electrons and react with 02. Other electron transport particles have been prepared by sonic oscillation. Under the electron microscope such particles appear to be small membranous vesicles resembling mitochondrial cristae. 

The source of enzyme activity was mycelium from Streptomyces clavuling-erus. The mycelium were disrupted by sonic oscillation. The supernate was clarified by centrifugation and for best results desalted and equilibrated on a Sephadex G-10 column with 0.1 Af Mops buffer (pH 7.0) in 25% (v/v) aqueous glycerol containing 20 mAf MgCl2, 30 mAf 2-mercaptoethanol, 2 mAf dithio-threitol, and 5 mAf EDTA. 

PHB The PHB is extracted from the dried cells by means of suitable chlorinated solvents and subsequent precipitation of the PHAs. As an alternative, the cell components can be dissolved in an appropriate oxidizing solvent or by using enzymatic decomposition of the cells including the cell components and sonic oscillation. However, enzymatic decomposition should be preferred taking into account the risks of using chlorinated solvents. 

Calf thymus and salmon sperm DNA were used in this experiment. The length of calf thymus ranges from 10,500 to 1500 A. and that of salmon sperm DNA from 7400 to 1300 A. A 20-kc. sonic oscillation is applied to produce smaller DNA samples. Viscosity is measured with a Rao couette-type viscometer with varying shearing stress. It is obtained by extrapolating the consistency curve to zero shear. 

Intracellular enzymes are prepared by plasmoptysis or sonic oscillation of spheroplasts or shocked cells. 

When UDP-2-acetamido-2-deoxy-D-glucose and UDP-N-acetyl-muramyl-pentapeptide are together added to broken bacterial-cell preparations, a new product is formed that contains the sugar and sugar-peptide portions of the precursors. If cells broken by means of a sonic oscillator are used, it is necessary to carry out the incubations on a filter-paper support " the precise function played by the filter paper is not yet known. In contrast, if enzymes are prepared by grinding cells with alumina, filter-paper support is unnecessary and the product contains a linear glycan backbone in which the two sugar residues occur in the alternate sequence expected. ... 

Among the many systems Racker used, one is a particulate system prepared by exposing beef mitochondria to sonic oscillation. The system can oxidize succinate and NADH but cannot couple the oxidation of the substrate to the phosphorylation of ADP. Coupling can be achieved by adding to the system two soluble proteins referred to by Racker as factor 1 (FJ and factor 4 (F4). F is a protein with ATPase activity obtained by sonic disintegration of mitochondria. F4 is prepared by alkaline extraction of the mitochondria. Fi, which has been extensively purified, is a decamer with a molecular weight of 284,000, each monomer weighing 26,000. 

Saito and associates (306) solubilized the enzjrme from liver mitochondria by sonic oscillation or extraction with 2% sodium cholate or digitonin. Severalfold purification was achieved by saltii -out between 0.35-0.55 saturation with (NH4)2S04. These investigators determined that molecular oxygen was required for the hydroxylation by experiments with O. The experimental work established that the reaction proceeds according to Eq. (22). 

Another degradative procedure for DNA is sonic oscillation which... 

The enzymic hydroxylation of kynurenine has been reported by several groups of workers (62,63). The enzyme is present in rat liver mitochondria and can be solubilized by sonic oscillation or digitonin treatment (63a). Reduced triphosphopyridine nucleotide (TPNH) is cifically required for the hydroxylation and there is a stoichiometric relationship between the TPNH oxidized and the hydro kynureiiine formed (62). Molecularo gen is also required for the hydroxylation, as indicated by 0 studies ( ). The... 

When mitochondria are disrupted into small vesicles or fragments with detergents, or by sonic oscillation, some enzymes and enzyme systems remain associated with the particles, while some others are recovered in the soluble phase. The cytochromes and the flavoproteins of the respiratory chain are exclusively recovered in the membrane fractions and seem to be firmly bound to the membrane. The ability to couple oxidation to phosphorylation is usually lost upon fragmentatioiu however, if the submitochondrial particles are prepared very carefully, they can... 

Fig. 7. Orientation of the elementary particles in submitochondrial fragments obtained by sonic oscillation and by digitonin treatment...

Fig. 4. (A) Rat-heart mitochondria, disrupted with sonic oscillation and negatively stained with isotonic ammonium molybdate. A detached crista is seen. Along its profiles, an array of protruding particles is evident. The particles are connected to the crista by a stalk. X 220,000. (B) A higher magnification detail of Figure 7. The particles measure about 90 A in diameter in some of them a substructure (subunits ) can be recognized, x 720,000. (Courtesy of Dr. U. M uscatello.)...

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