Walter W. Fredricks

Multiple forms of ferredoxin-nicotinamide adenine dinucleotide phosphate reductase from spinach☆

Abstract Crude extracts of ferredoxin-NADP reductase prepared from spinach by three different methods consistently contained two molecular weight forms of the enzyme: P-1, 117,500, and P-2, 50,000. The lower molecular weight form was purified and shown to consist of two different ionic forms. These three forms of the flavoprotein are immunologically identical. A third molecular weight form of the reductase, excluded by Sephadex G-100, generated P-1 and P-2 on rechromatography. Other experiments demonstrated that this enzyme has NADPH-tetrazolium reductase activity and it accounts for essentially all of the tetrazolium reductase activity of isolated chloroplasts.

The antigens of pigeon breeder's disease. I. Studies on unfractionated pigeon dropping extracts.

Approximately 6% of the dry organic dust from pigeon coops was extracted in the form of soluble, nondialyzable components. These pigeon dropping extracts contain a number of stable protein and glycoprotein antigens together with pigments and other components that cause nonspecific precipitation of normal and immune sera. Based on their migration in immunoelectrophoresis, the antigens have been designated PDEB, 1, 2, 3 or 4.

The isolation and characterization of glutamine-requiring strains of Escherichia coli K12

SummaryMutants of Escherichia coli K12 requiring glutamine as a nitrogen source were isolated, and characterized as lacking glutamine synthetase activity. Temperature sensitive revertants of one of the mutants had a heat labile glutamine synthetase, while temperature insensitive revertants had a glutamine synthetase which was thermostable in vitro, indicating that the mutation was in the structural gene for the enzyme. All of the mutations mapped in the same region of the chromosome suggesting that they might all be in the same gene. The glutamine synthetase gene (gln) was located on the E. coli chromosome by conjugation and P1-mediated transduction at minute 77. The gln gene cotransduced with the genes for oleate degradation (old), and the genes for L-rhamnose utilization (rha). The most probable gene order is old-gln-rha.

Secondary-site attachment of coliphage lambda near the thr operon

Abstract Phage λ has been integrated at a secondary attachment site near the thr oporon of Escherichia coli . The integration caused a pleiotropic effect since both thrA and thrB enzyme activities were lost. Lysogenic, thr + revertants regained thrA and thrB activities although the enzymes were synthetized constitutively at low levels. Four classes of prophage deletion strains were isolated with deletions extending into trpR and the thr operon. Genetic and biochemical analyses indicated a gene order: trpR .. λ .. thrA .. B .. C . Defective transducing phage carrying thr A, B,C were also isolated.

Kinetics of extraction of ferredoxin-nicotinamide adenine dinucleotide phosphate reductase from spinach chloroplasts

Abstract The kinetics of extraction of ferredoxin-NADP reductase from chloroplasts was studied under standardized conditions. The process appeared to be irreversible and did not follow first-order kinetics. The rate was increased by addition of ethanol to the extraction buffer or by elevated temperatures and pH, but extraction was retarded by high concentrations of sucrose or inorganic salts. The kinetics of extraction was unaffected by a wide variety of modifications of the standardized conditions, including freezing and thawing. Chloroplasts isolated by precipitation in 95% acetone released the reductase more rapidly than those isolated in buffered sucrose solutions.

Enzyme antigens associated with pigeon Breeder's disease. II. Isolation and characterization of acidic hydrolases

A survey of the hydrolytic enzymes present in pigeon dropping extracts (PDE) has shown that this material contains a variety of proteolytic and nonproteolytic activities. These enzymes were separated into their basic and acidic components by chromatography on DEAE-cellulose. Staining of immunoprecipitates with specific chromogenic substrates demonstrated the presence of antibodies in symptomatic breeders to several of the basic enzymes in PDE. Five distinct hydrolytic activities were isolated from the basic group of enzymes. Trypsin, elastase, and two forms of collagenase were the specific proteolytic activities isolated. A phospholipase was also purified from these preparations. The purified elastase consisted of a single polypeptide chain (Mr=22,000). The purified trypsin had a molecular weight (Mr=25,000) and charge similar to those reported for elastase and, like elastase, the trypsin from PDE appeared to be composed of a single polypeptide chain. Two molecular weight forms of collagenase were found; both hydrolyzed bovine collagen. The high-molecular-weight collagenase (Mr=51,000) was shown to be a glycoprotein consisting of two polypeptides (Mr=24,000). It was readily separated from the low-molecular-weight collagenase (Mr=15,000) by gel filtration. The phospholipase (Mr=99,000) appeared to be a dimer. The relevance of these enzymes to the development of pigeon breeders disease is discussed.