Mitochondria isolated from Saccharomyces cerevisiae and purified in Urografin or sucrose gradient contain tRNA methylating activity with specificities different from those of the cytoplasm. The main reaction product, using E.coli tRNA as methyl group acceptor, is N(2),-N(2)-dimethylguanine. The corresponding mitochondrial methylase is coded by nuclear DNA. A DNA methylating activity is also ass...

Purified chloroplasts were disrupted and then fractionated by discontinuous sucrose-density-gradient centrifugation. Envelopes contained long-chain acyl-CoA synthetase at a specific activity 80 times the activity in the lamellae or the stroma. Acetyl-CoA synthetase was concentrated in the stroma, and chlorophyll was confined to the lamellae membranes. Phospholipase D was not detected in any fra...

Tissue cultures established from brain tissues of six patients with various chronic, degenerative diseases did not show evidence of viral agents. Sucrose gradient analysis of radioactively labeled culture fluid from two patients failed to reveal the presence of any incomplete or defective virus. Extracellular fluids from three brain cultures contained a factor able to stimulate deoxyribonucleic...

A method was developed to obtain purified cryptosporidium oocysts from fecal samples. Oocysts were initially collected by centrifugation through a sucrose density gradient and further purified by passage through glass bead columns. The purified oocysts were antigenically active and sufficiently pure for immunological studies.

Purified prostatic acid phosphatase catalyzes the hydrolysis of thymolphthalein monophosphate 10-fold faster if an optimal concentration of Brij 35 (a wetting agent) or protein (bovine serum albumin or human serum proteins) is present. Results of gel filtration, dialysis, and sucrose density-gradient centrifugation analysis suggest that the substrate must combine with detergent or protein befor...

1. Liver biopsies from two patients with the Dubin-Johnson-Sprinz syndrome were subjected to analytical subcellular fractionation by sucrose-density-gradient centrifugation and enzymic microassays. 2. A selective deficiency of mitochondrial superoxide dismutase has been demonstrated in these patients. 3. The significance of this enzyme deficiency is discussed in relation to the organelle pathol...

Cell membranes from Caulobacter can be isolated and separated into inner and outer membranes according their characteristic buoyant densities on a sucrose gradient. Fractionation can be used to determine the localisation of uncharacterised proteins and to enrich protein complexes present in either of these membranes for biochemical analysis such blue-native PAGE and immunoprecipitation.

Axonemal dynein from Tetrahymena cilia can be separated on a sucrose gradient into two fractions, at least one of which appears to be polymorphic. We have been using immuno-electron microscopy in order to try and locate the different types of dynein molecules within the axonemal structure.

The localization of some key enzymes leading to sucrose synthesis in photosynthetic tissue of C(3) and C(4) species was investigated. These included UDP-glucose (UDPG) pyrophosphorylase, sucrose phosphate synthetase, and glycerate kinase. Whether glycerate kinase is localized exclusively in the chloroplast or partly outside the chloroplast could influence the fate of carbon flow to sucrose thro...

The role of T7-induced exonuclease (gene 6) in molecular recombination was studied by examining the fate of parental DNA during parental-to-progeny recombination. The method used was to compare infections with T7(+), T7am-6-233 (am gene 6), or T7ts6-136 (ts gene 6) under permissive and nonpermissive conditions. CsCl density gradient analysis of replicative DNA indicated that T7 exonuclease is n...