A novel dNTP pyrophosphatase, Mj0226 from Methanococcus jannaschii, which catalyzes the hydrolysis of nucleoside triphosphates to the monophosphate and PPi, has been characterized. Mj0226 protein catalyzes hydrolysis of two major substrates, dITP and XTP, suggesting that the 6-keto group of hypoxanthine and xanthine is critical for interaction with the protein. Under optimal reaction conditions...

Although drugs are a common cause of acute immune-mediated thrombocytopenia in adults, the drug etiology is often initially unrecognized. Most cases of drug-induced thrombocytopenia (DITP) are caused by drug-dependent antibodies that are specific for the drug structure and bind tightly to platelets by their Fab regions but only in the presence of the drug. A comprehensive database of 1301 publi...

Drug-induced immune thrombocytopenia (DITP) is a relatively common and sometimes life-threatening condition caused by antibodies that bind avidly to platelets only when drug is present. How drugdependent antibodies (DDAbs) are induced and how drugs promote their interaction with platelets are poorly understood, and methods for detecting DDAbs are suboptimal. A small animal model of DITP could p...

The mechanism of drug-dependent immunologic thrombocytopenic purpura (DITP) was investigated by studying the sera of four patients with classic DITP (two with quinidine-, one with acetaminophen-. and one with phenazopyridinedependent antiplatelet antibody) using a solid-phase radioimmunoassay with 125l-staphylococcal protein A. Two forms of antiplatelet antibody could be demonstrated: one that ...

Deoxyinosine (dI) occurs in DNA either by oxidative deamination of a previously incorporated deoxyadenosine residue or by misincorporation of deoxyinosine triphosphate (dITP) from the nucleotide pool during replication. To exclude dITP from the pool, mammals possess specific hydrolysing enzymes, such as inosine triphosphatase (ITPA). Previous studies have shown that deficiency in ITPA results i...

The mechanism of drug-dependent immunologic thrombocytopenic purpura (DITP) was investigated by studying the sera of four patients with classic DITP (two with quinidine-, one with acetaminophen-, and one with phenazopyridine-dependent antiplatelet antibody) using a solid-phase radioimmunoassay with 125I-staphylococcal protein A. Two forms of antiplatelet antibody could be demonstrated: one that...

Drug-induced immune thrombocytopenia (DITP) is a relatively common and sometimes life-threatening condition caused by antibodies that bind avidly to platelets only when drug is present. How drug-dependent antibodies (DDAbs) are induced and how drugs promote their interaction with platelets are poorly understood, and methods for detecting DDAbs are suboptimal. A small animal model of DITP could ...

Drug-induced thrombocytopenia (DITP) is a well-established but underdiagnosed condition. The condition is mostly asymptomatic, but can also cause severe bleeding [1]. Thrombocytopenia is a wellknown side effect of treatment with several types of medications. Therapeutic agents, speci ically those used for chemotherapy and immunosuppressants, tend to repress hematopoiesis and generate pancytopen...

Inosine triphosphatase (ITPase) is the enzyme that catalyzes the conversion of inosine triphosphate (ITP) and deoxy-inosine triphosphate (dITP) to inosine monophosphate and deoxy-inosine monophosphate, respectively, thereby maintaining low intracellular concentrations of ITP and dITP. Individuals deficient in ITPase activity were first recognized over 30 years ago. For decades, no clinical sign...

A hypothetical 21.0 kDa protein (ORF O197) from Escherichia coli K-12 was cloned, purified, and characterized. The protein sequence of ORF O197 (termed EcO197) shares a 33.5% identity with that of a novel NTPase from Methanococcus jannaschii. The EcO197 protein was purified using Ni-NTA affinity chromatography, protease digestion, and gel filtration column. It hydrolyzed nucleoside triphosphate...