DNA, RNA and protein synthesis in OLL55-infected Lactobacillus lactis.
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Biomedical subjects
Publications and source records attributed to S S Sarimo.
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Human salivary proteins were enzymically iodinated by the 125I-lactoperoxidase system. The proteins were than subjected to DEAE-cellulose column chromatography, preparative column electrofocusing and thin-layer polyacrylamide-gel electrofocusing. The radioactivity in the resolved protein pools and bands was determined. Results show that salivary proteins differ in their susceptibility to iodination carried out by this enzymic method. Two major iodine-binding protein fractions were discovered: one behaved like serum albumin on electrofocusing and was most susceptible to iodination by lactoperoxidase, and other had pI characteristics similar to those of salivary amylase. The physiological significance of the iodination of salivary proteins, which can also take place in vivo, is discussed.
Purified milk lactoperoxidase and endogenous human salivary peroxidase were used to label the proteins of whole mouth saliva with [125I]iodide. The proteins were then analyzed by isoelectric focusing or they were subjected to one-dimensional polyacrylamide gel electrophoresis at pH 8.4. The radioactivity of the resolved protein fractions was determined. There were three to four major and four to five minor areas of radioactivity which were carried together with more or less distinctive protein fractions. Amylase and albumin were shown to be the most effective in binding [125I]iodide. No significant differences were observed in the iodination patterns of salivary proteins iodinated in the presence of endogenous saliva peroxidase and those iodinated in the presence of added milk lactoperoxidase. Hydrogen peroxide was necessary for iodination to take place. The significance of iodoproteins and the role of salivary peroxidases in the nonthyroidal metabolism of iodine are discussed.
The amino and keto acid composition of the cells of Streptococcus mutans, strain Ingbritt, maintained and grown on a Trypticase-Phytone based medium without any added carbohydrate or supplemented with xylitol or glucose, was analyzed. The results showed no remarkable differences in the portions of individual amino acids liberated by acid hydrolysis from the cellular proteins of cells grown in the above mentioned media. However, the amount of free amino acids in the water extracts of the cells grown in the glucose medium differed considerably from those obtained from cells grown in the two other media. The amounts of free amino acids of the medium at the end of the growth period were higher in the glucose containing medium than in the two other media. The content of keto acids was lower in the cells grown in the presence of xylitol or without added carbohydrate when compared to those cells grown in glucose containing medium.
High-titer lysates of a bacteriophage active against Lactobacillus lactis were prepared from liquid cultures as well as from areas of confluent lysis in soft-agar overlayers. Phage concentration and purification were accomplished by means of polyethylene glycol precipitation, differential centrifugation. The buoyant density of this phage in cesium chloride was 1.4795 g/ml. Characterization of phage growth cycle by one-step growth experiments under optimal conditions showed that the latent period was about 120 min, that the rise period lasted approx. 130 min, and that the average burst-size was about 80.
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A comparison was made of the distribution of amino terminal end groups in the cellular proteins of a number of microbes. Among the procaryotes, methionine is a highly variable but virtually ubiquitous major protein end group. This is consistent with its possible role as a general amino acid initiator of protein biosynthesis in the procaryotes. Generally, however, alanine is the most abundant of the major end groups, followed in decreasing order by serine, threonine, the acidic amino acids, and occasionally lysine. No other new major end-groups were found. Among 15 representatives of the Enterobacteriaceae, retention of the initiating methionine terminus of the cellular protein varies considerably at a tribal level and is randomized at a familial level. The profiles of the five remaining end groups, however, are strikingly uniform, and are, for example, close to but significantly different from those of the Erwineae. Among the taxonomically more heterogeneous Bacillaceae, end-group profiles vary more and are sometimes unrelated. End-group analysis is thus particularly useful as a molecular criterion of taxonomy in assessing familial homogeneity. Free NH(2) termini in eucaryote cell proteins are fewer, and they have increased acidic amino acid components and no methionine; they are otherwise similar to those of the procaryotes.