Human organic anion transporter 4 (hOAT4) belongs to a family of organic anion transporters which play critical roles in the body disposition of clinically important drugs, including anti-HIV therapeutics, antitumour drugs, antibiotics, anti-hypertensives and anti-inflammatories. hOAT4-mediated transport of the organic anion oestrone sulphate in COS-7 cells was inhibited by the histidine-modify...

Proline 4-hydroxylase is a 2-oxoacid, ferrous-ion-dependent dioxygenase involved in the biosynthesis of the secondary metabolite etamycin. The purification, in low yield, of proline 4-hydroxylase from Streptomyces griseoviridus P8648 to near, apparent homogeneity and its initial characterization are reported. In most respects proline 4-hydroxylase is a typical member of the 2-oxoacid-dependent ...

N-Bromosuccinimide completely inactivated the cellulase, and titration experiments showed that oxidation of one tryptophan residue per cellulase molecule coincided with 100% inactivation. CM-cellulose protected the enzyme from inactivation by N-bromosuccinimide. The cellulase was inhibited by active benzyl halides, and reaction with 2-hydroxy-5-nitrobenzyl bromide resulted in the incorporation ...

In this paper we report on the thermal unfolding of the tRNA-like structure present at the 3' end of turnip yellow mosaic virus (TYMV) RNA. Diethyl pyrocarbonate (DEP), sodium bisulphite, nuclease S1 and ribonuclease T1 were used as structure probes at a broad range of temperatures. In this way most of the nucleotides present in the tRNA-like moiety were analysed. The melting behaviour of both ...

System A and N amino acid transporters are key effectors of movement of amino acids across the plasma membrane of mammalian cells. These Na+-dependent transporters of the SLC38 gene family are highly sensitive to changes in pH within the physiological range, with transport markedly depressed at pH 7.0. We have investigated the possible role of histidine residues in the transporter proteins in d...

The chloroplastic NADP malate dehydrogenase is completely inactive in its oxidized form and is activated by thiol/disulfide interchange with reduced thioredoxin. To elucidate the molecular mechanism underlying the absence of activity of the oxidized enzyme, we used site-directed mutagenesis to delete or substitute the two most C-terminal residues (C-terminal Val, penultimate Glu, both bearing n...

The molecular analysis of formalin-fixed and paraffin-embedded tissues has application in both investigative studies and clinical practice (1). It is now possible to analyze gene expression in formalin-fixed and paraffin-embedded tissues by in situ reverse transcriptase-polymerase chain reaction (in situ RT-PCR) (2). Degradation of RNA, however, can occur at various stages of tissue preparation...

LpxE, a membrane-bound phosphatase found in Rhizobium leguminosarum and some other Gram-negative bacteria, selectively dephosphorylates the 1-position of lipid A on the outer surface of the inner membrane. LpxE belongs to the family of lipid phosphate phosphatases that contain a tripartite active site motif and six predicted transmembrane helices. Here we report the purification and characteriz...

Chemical modification of spinach ribulosebisphosphate carboxylase/oxygenase by diethyl pyrocarbonate led to the conclusion that His-298 is an essential activesite residue (Igarashi, Y., McFadden, B. A., and ElGul, T. (1985) Biochemistry 24, 3957-3962). From the pH dependence of inactivation, the pKa of His-298 was observed to be -6.8, and it was uggested that this histidine might be the essenti...

The bisphosphatase activity of the hepatic bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase is repressed by its kinase domain, and regulated by cAMP-dependent protein kinase (PKA)-catalysed phosphorylation. In the present study, the mechanism by which the bisphosphatase activity is repressed by the kinase domain and regulated by phosphorylation was investigated. We found...