A specific ribonucleoside triphosphate reductase is induced in anaerobic Escherichia coli. This enzyme, as isolated, lacks activity in the test tube and can be activated anaerobically with S-adenosylmethionine, NADPH, and two previously uncharacterized E. coli fractions. The gene for one of these, previously named dA1, was cloned and sequenced. We found an open reading frame coding for a polype...

A simple procedure for purification of ferredoxin from a green alga, Scenedesmus, is described. Crystalline ferredoxin had an absorption spectrum with maxima at 276, 330, 421, and 464 rnp and with minima at 255, 293, 390, and 445 rnp. The ratios of the optical densities at 421 and 330 rnp to that at 276 rnp were 0.651 and 0.883, respectively. The substance was shown to be pure by disc electroph...

The unusual property of halophilic proteins to withstand high concentrations of salt, and in some cases the requirement of salt to maintain their conformation (Werber et al., 1978a), has prompted us to study their three-dimensional structure. Recently, a 2 Fe-ferredoxin has been isolated and purified from Halobacterium of the Dead Sea (Werber & Mevarech, 1978a), and other species of Halobacteri...

Native ferredoxin isolated from Clostridium acidi-urici cannot be acetylated and is not digested by carboxypeptidase A. However, apoferredoxin, free of iron and sulfide, can be acetplated and the COOH-terminal alanine and glutamine residues are quantitatively removed by carboxypeptidase A. Ferredoxin derivatives can be reconstituted from both modified proteins. The following derivatives were al...

The investigation reported in this communication was concerned with the biosynthesis of ferredoxin in a cell-free system. A cell-free system, with the ability to incorporate amino acids into peptides and proteins, was developed from Cl. pasteurianum, and its requirements were established. After the incorporation of L-alanine-C(14), ferredoxin-C(14) was isolated in crystalline form with the aid ...

Chenopods synthesize betaine in the chloroplast via a two-step oxidation of choline: choline --> betaine aldehyde --> betaine. Our previous experiments with intact chloroplasts, and in vivo(18)O(2) labeling studies, led us to propose that the first step is mediated by a monooxygenase which uses photosynthetically generated reducing power (C Lerma, AD Hanson, D Rhodes [1988] Plant Physiol 88: 69...

Objective(s): In recent years, the application of radiopharmaceuticals in nuclear medicine has increased substantially. Following the diagnostic procedures performed in nuclear medicine departments, such as myocardial perfusion imaging, patients generally receive considerable doses of radiation. Normally, radiation-induced DNA damages are expected following exposure to a low-dose ionizing radia...