Use of formylated yeast initiator Met tRNA to define the NH2-terminal residues of rat preproinsulin and pregrowth hormone

A method for unambiguously determining the initiator methionine residue and the adjacent NH2-terminal amino acid sequence of cell-free translation products of eukaryotic messenger RNA is described. In this procedure, the NH2 termini of nascent peptides are blocked by incorporating labeled formylmethionine instead of methionine, using yeast initiator tRNA in the wheat germ cell-free system. After immunoprecipitation of the desired product the radiolabeled material is treated with dansyl-Cl to irreversibly block all remaining free amino groups. The material is then deformylated by mild acid hydrolysis and subjected to automated Edman degradation. Only those products that had been synthesized with formylmethionine residues at their NH2-termini can then give rise to labeled phenylthiohydantoin derivatives during degradation. Using this method, we have defined the initiation sites in both rat preproinsulin and pregrowth hormone messenger RNAs.     

Deoxyribonuclease I binding masks the major tryptic cleavage sites on actin

The formation of a 1:1 molecular complex of deoxyribonuclease I with muscle G-actin protects both proteins against proteolytic attack by trypsin. After 1$\text{1}\text{2}$ hours of digestion, negligible proteolysis of the complex is observed by sodium dodecyl sulfate polyacrylamide gel electrophoresis, while G-actin alone is rapidly broken down to a trypsin resistant core. The binding of deoxyribonuclease I to actin apparently masks the major tryptic cleavage sites (arginine-62 and lysine-68) on the latter protein.     

Citrate-tris(hydroxymethyl)aminomethane-mediated release of outer membrane sections from the cell envelope of a deep-rough (heptose-deficient lipopolysaccharide) strain of Escherichia coli O8.

A heptose-deficient lipopolysaccharide strain of Escherichia coli O8, strain F515, was found to release portions of its outer membrane when cells were exposed to 10 mM citrate buffer (pH 2.75) for 30 min and subsequently exposed to 100 mM tris(hydroxymethyl)aminomethane buffer (pH 8.00). The outer membrane component release was found to be composed of protein, lipopolysaccharide, phospholipid (cardiolipin, phosphatidylethanolamine, and phosphatidylglycerol), and alkaline phosphatase. The outer membrane component was released from the cell envelope in the absence of cell lysis, as no glucose-6-phosphate dehydrogenase activity or succinic dehydrogenase activity was detected. Morphologically, the outer membrane component appeared to consist of laminar fragments and vesicles which had an associated alkaline phosphatase activity.     

Coordinate increases in the enzyme activities responsible for phosphatidylglycerol synthesis and CTP:cholinephosphate cytidylyltransferase activity in developing rat lung

The enzymes responsible for the biosynthesis of phosphatidylglycerol, CTP:phosphatidate cytidylyltransferase, CDP-diacylglycerol: glycerophosphate phosphatidyltransferase and phosphatidylglycerophosphate phosphatase demonstrated a coordinate increase in activity in fetal rat lung at term when the demand for pulmonary surfactant increases. The activity of CTP:cholinephosphate cytidylyltransferase, the enzyme responsible for CDP-choline production also increased in the perinatal period. The activity of cholinephosphate cytidylyltransferase in fetal and neonatal cytosol was stimulated by the addition of phosphatidylglycerol but no effect was noted with cytosol from adult lung. These results are consistent with the suggestion that the activity of cholinephosphate cytidylyltransferase, a potential rate-determining enzyme in pulmonary phosphatidylcholine synthesis, may be regulated in the perinatal period both through an activation by phosphatidylglycerol and by an increase in total enzyme units.     

Genetics of glucosephosphate isomerase in Aedes togoi (Diptera: Culicidae)

The genetics of glucosephosphate isomerase (E.C. 5.3.1.9) in two strains (Malaysian and Taiwan) of Aedes togoi is reported. Three electrophoretic phenotypes were present in both sexes. The zymogram patterns were identical in both strains of A. togoi. The phenotypes were governed by a pair of codominant alleles. The allele frequency of the slow-moving band was 0.63 in the Malaysian strain and was 0.86 and 0.82 in F161 and F169 generations, respectively, of the Taiwan strain. The sample studied was in good accord with Hardy-Weinberg expectations.     

The extraction and analysis of lipopolysaccharides from Pseudomonas aeruginosa strain PAO, and three rough mutants.

Three spontaneously arising rough mutants of Pseudomonas aeruginosa have been isolated by selection for resistance to virulent lipopolysaccharide (LPS) specific bacteriophages. In addition, the first phages specific for rough mutants of P. aeruginosa were isolated. Using these phage and autoagglutination patterns in 4% NaCl and acriflavine, these mutants could be clearly distinguished from the wild-type strain and each other. Chemical analysis of the LPS together with chromatographic resolution of the polysaccharide moieties showed alterations in both O-specific side chains and core regions.     

Purification of a phosphoprotein from chromatin of rat liver.

A simple and effective method to purify a phosphoprotein (B2) (Mr 68,000, pI 6.2-8) from phenol-soluble non-histone chromatin proteins of rat liver is described. The purification involved only two steps, CM-cellulose chromatography and preparative SDS/polyacrylamide (10%)-gel electrophoresis. The purified phosphoprotein B2 was shown to be homogeneous by SDS/polyacrylamide-gel electrophoresis. The yield was 2% of total non-histone chromatin proteins. The acidic to basic amino acid ratio of phosphoprotein B2 was less than 1, with high contents of glutamic acid, aspartic acid, arginine, lysine, glycine and alanine. The phosphate content of this protein is 0.3%.