Studies on a membrane-bound and solubilized ribonucleotide reductase preparation from Escherichia coli TAU-.

Ribonucleotide reductase has been shown to be associated with the DNA-membrane complex in Escherichia coli TAU- cells. The membrane-bound enzyme has been released in a soluble form using a combined treatment of 1% sarcosyl (pH 8.0) and 1% sodium deoxycholate (pH 6.

An ATPase dependent, radiosensitive acidic microclimate essential for intestinal folate absorption.

1. 5-Methyltetrahydrofolic acid transport was studied across everted sacs of rat jejunal segments from control and whole body X-irradiated (700 rad) rats at 10(-5)M concentrations (at which optimum transport occurs) at various pHs.2.

Studies on the enzymatic hydrolysis of polyglutamyl folates by chicken liver folyl poly-gamma-glutamyl carboxypeptidase. I. Intracellular localization, purification and partial characterization of the enzyme.

Intracellular distribution, purification and properties of a folyl poly-gamma-glutamyl carboxypeptidase (peptidyl-L-glutamate hydrolase, EC 3.4.12.

Studies on the enzymatic hydrolysis of polyglutamyl folates by chicken liver folyl poly-gamma-glutamyl carboxypeptidase. II. Structural studies.

Further studies on the purified chicken hepatic folyl poly-gamma-glutamyl carboxypeptidase (peptidyl-L-glutamate hydrolase, EC 3.4.12.

Induction of a reductive pathway for deoxyribonucleotide synthesis during early embryogenesis of the sea urchin.

Cell-free extracts of Arbacia eggs (Arbacia punctulata) apparently do not contain an enzymatic system for the reduction of ribonucleotides to deoxyribonucleotides. However, during an interval of 5 hr after fertilization at 23 degrees , an enzymatic system is produced that is capable of catalyzing the reduction of CDP to dCDP in the presence of Mg(2+), ethylenediaminetetraacetate, ATP, and a reducing agent, dithiothreitol. The activity is first seen about 1 hr after fertilization, and reaches a peak at about 5 hr.