A preparation of polynucleotide phosphorylase from Micrococcus Zysodei&icus that reversibly catalyzes the formation of long chain polynucleotides from nucleoside 5’-diphosphates has been described previously (2). The general features of the reaction appear similar to those reported earlier by GrunbergManago et al. (3, 4), who used preparations from Azotobacter vinelandii. The over-all reaction ...

Threonine deaminase (Lthreonine hydrolyase (deaminating), EC 4.2.1.16) has been purified approximately 700-fold from extracts of Clostridium tetanomorphum. Both threonine and serine can serve as substrates, but threonine is deaminated 5 to 10 times more rapidly than serine. Pyridoxal phosphate, a reducing agent, and alkaline pH are required for the deamination of either amino acid. A plot of th...

Ribonucleoside diphosphate reductase is an allosteric enzyme consisting of two nonidentical subunits, proteins B1 and B2. B1 contains dithiols which participate in the oxidation-reduction reactions of electron transport, while B2 contains a free radical essential for activity. Ribonucleoside diphosphates are bound to B1 but not to B2. Addition of 2'-deoxy-2'-chloro ribonucleoside diphosphates t...

cis-Prenyltransferase catalyzes the sequential condensation of isopentenyl diphosphate with allylic diphosphate to synthesize polyprenyl diphosphates that play vital roles in cellular activity. Despite potential significance of cis-prenyltransferase in plant growth and development, no gene of the enzyme has been cloned from higher plants. Using sequence information of the conserved region of ci...

Polynucleotide phosphorylase catalyzes the reversible polymerization of nucleoside diphosphates (1). With enzyme preparations from Escherichia coli (2), Azotobacter agile (3), and Micrococcus lysodeikticus (4, 5) a reaction has been observed with single additions of adenosine, uridine, cytosine, or inosine diphosphate to form the corresponding homopolymer. However, the polymerization of guanosi...

An analysis of the x-ray structure of homodimeric avian farnesyl diphosphate synthase (geranyltransferase, EC 2.5.1.10) coupled with information about conserved amino acids obtained from a sequence alignment of 35 isoprenyl diphosphate synthases that synthesize farnesyl (C15), geranylgeranyl (C20), and higher chain length isoprenoid diphosphates suggested that the side chains of residues corres...

The relative abilities of some compounds to inhibit the transformation of amorphous calcium phosphate into hydroxyapatite were determined. Organic diphosphates, fructose 1,6-bisphosphate, pyrophosphate, imidodiphosphate and 3-phospholycerate all inhibited to various degrees. Strong inhibition was observed with phosphonoformate, and phosphocitrate proved to be the most powerful of the inhibitors...