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Biomedical subjects

H P KLEIN

Publications and source records attributed to H P KLEIN.

At least 19 recordsLinked to original sources
PubMed1964

EFFECTS OF ASPARTATE ON GROWTH AND ON THE SYNTHESIS OF ALPHA-AMYLASE IN PSEUDOMONAS SACCHAROPHILA.

Eisenstadt, Jerome M. (Brandeis University, Waltham, Mass.), and Harold P. Klein. Effects of aspartate on growth and on the synthesis of alpha-amylase in Pseudomonas saccharophila. J. Bacteriol. 87:1355-1363. 1964.-Protein synthesis by starch-grown cells of Pseudomonas saccharophila is inhibited by low concentrations of d-aspartate, whereas assimilation continues for several hours under these conditions. These effects are also observed when the cells are grown with cellobiose or maltose, but not with a wide variety of other carbon sources. l-Aspartate at a ratio of about 6:1 completely reverses these effects, whereas adenosine partially does so. One possible basis of the inhibitory effects of d-aspartate is in the synthesis of adenosine from inosine.

Amylases↗
PubMed1961

Evidence for the de novo synthesis of the alpha-amylase of Pseudomonas saccharophila.

Eisenstadt, Jerome M. (Brandeis University, Waltham, Mass.) and Harold P. Klein. Evidence for the de novo synthesis of the alpha-amylase of Pseudomonas saccharophila. J. Bacteriol. 82:798-807. 1961.-Chloramphenicol at a concentration of 20 mug per ml inhibited the appearance of the inducible alpha-amylase of Pseudomonas saccharophila. This inhibition was observed when induction was attempted in buffer or in a complete medium. Preinduced cells were also prevented from forming this enzyme under similar conditions. Under all the conditions tested, there was no lag in chloramphenicol inhibition, thus suggesting an absence of any protein precursor in amylase formation. Cells suspended in a complete medium without a nitrogen source lost their capacity to form this enzyme when subsequently induced in buffer. When cells were grown in the presence of radioactive sulfate and then subjected to starvation, the radioactivity of the amino acid pool diminished only slightly. However, examination of the free amino acid pool by paper chromatography showed that the loss of enzyme inducibility was accompanied by the disappearance of glutamine, aspartic acid, and a third, unidentified, compound. Enzyme-forming ability was restored by the addition, to starved cells of casein hydrolysate, glutamate, glutamine, or aspartate. Other amino acids tested were ineffective in this regard. When cells were induced in buffer in the presence of labeled methionine, amylase was formed at a linear rate over a 3-hr period. Furthermore, both the cellular proteins and the extracellular amylase became labeled at a linear rate. These observations are discussed in relation to the problem of protein turnover, and are interpreted as evidence for the de novo synthesis of alpha-amylase in this organism.

Amino Acids↗
PubMed1958

Cobalt activation of fatty-acid synthesis in yeast homogenates.

The incorporation of acetate into lipids in homogenates of Saccharomyces cerevisiae was inhibited at low concentrations of ethylenediaminetetraacetate, under both aerobic and anaerobic conditions. Of various cations tested, none could effectively reverse this inhibition. However, Co(++) completely restored the synthesis of fatty acids, but not of nonsaponifiable lipids.

Cobalt↗