An acid-alkaline transition and temperature-dependent changes in the spin state of ferric L-tryptophan 2,3-dioxygenase, a protohemoprotein, have been demonstrated by employing highly purified enzyme preparations from both Pseudomonas and rat liver. In an acidic pH, the enzyme exhibited absorption spectra typical to a high spin ferric protohemoprotein having absorption maxima at 407,502, and 632...

Excess acetate has long been an issue for the production of recombinant proteins in E. coli cells. Recently, improvements in acetate tolerance have been achieved through the use of genetic strategies and medium supplementation with certain amino acids and pyrimidines. The aim of our study was to evaluate an alternative to improve the acetate tolerance of E. coli BL21 (DE3), a popular strain use...

Although the aetiology of Barrett's oesophagus or columnar line oesophagus (CLO), remains unknown, bile reflux has been implicated as a factor in its pathogenesis. This study aimed to detect alkaline reflux in gastro-oesophageal reflux patients using dual probe pH monitoring. Thirty patients with histologically diagnosed CLO, 15 age and sex matched patients with oesophagitis (grade 1-3), and 15...

1. Isoelectric focusing of human liver alkaline phosphatase in a sucrose density gradient with LKB Ampholine as carrier ampholytes is described. 2. Problems due to the chelating properties of the ampholytes and the pH gradient were examined. 3. A reactivation procedure to counter these effects was devised that can probably be used for other alkaline phosphatases. 4. The isoelectric point of hum...

A teichuronopeptide (TUP) is one of major structural components of the cell wall of the facultative alkaliphilic strain Bacillus lentus C-125. A mutant defective in TUP synthesis grows slowly at alkaline pH. An upper limit of pH for growth of the mutant was 10.4, while that of the parental strain C-125 was 10.8. Gene tupA, directing synthesis of TUP, was cloned from C-125 chromosomal DNA. The p...

The recovery of cellulases from lignin, lignocellulosic hydrolysates and cellulose by alkaline washes at pH 9 and 10 was examined. The effect of the pH on the structural stability of purified Cel7A was analyzed by circular dichroism. Purified Cel7A showed conformational changes at pH 9 and 10 that were reversible at pH 4.8. Temperature influenced the enzymatic hydrolysis of wheat straw and may ...

Alkaline phosphatase [orthophosphoricmonoester phosphohydrolase (alkaline pH optimum), EC 3.1.3.1] purified from a Burkitt lymphoma cell line (Daudi) and Moloney-virus-induced murine leukemia (YAC) showed unique catalytic properties in substrate specificity and inhibition by cysteamine-S-phosphate. It migrated on polyacrylamide gel electrophoresis in a single activity band. Alkaline phosphatase...

Many anticancer drugs are classified as either weak bases or molecules whose binding to cellular structures is pH dependent. Accumulation of these drugs within tumor cells should be affected by transmembrane pH gradients. Indeed, development of multidrug resistance (MDR) in tumor cells has been correlated with an alkaline shift of cytosolic pH. To examine the role of pH in drug partitioning, th...

Candida albicans is a commensal fungus that causes diverse infections after antibiotic use or immune debilitation. Gene discovery has been limited because the organism is an asexual diploid. We have developed a strategy that yields random homozygous insertion mutants. The strategy has permitted identification of several prospective essential genes. Many of these genes are homologous to nonessen...

Phospholipase B (PLB) from the asporogenous yeast Candida utilis was purified to homogeneity from a culture broth. The apparent molecular mass was 90-110 kDa by SDS-PAGE. The enzyme had two pH optima, one acidic (pH 3.0) and the other alkaline (pH 7.5). At acidic pH the enzyme hydrolyzed all phospholipids tested without metal ions. On the other hand, the PLB showed substrate specificity and req...