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D R Storm

Publications and source records attributed to D R Storm.

172 records · Page 10Linked to original sources
PubMed1974

Inhibition of the Bacillus subtilis membrane-bound D-alanine carboxypeptidase by 6-aminopenicillanic acid covalently coupled to sepharose.

An insoluble penicillin derivative, 6-aminopenicillanic acid covalently coupled to Sepharose, was used to investigate the location of the d-alanine carboxypeptidase in the Bacillus subtilis membrane. Only 50% of the enzymatic activity in protoplasts and 74% of that in purified membranes was sensitive, although the purified enzyme could be inhibited completely by the resin. These results suggest that a minimum of 50% of the d-alanine carboxypeptidase exists on the outer face of the bacterial membrane.

Alanine↗
PubMed1970

A source for the special catalytic power of enzymes: orbital steering.

The velocities of acid catalyzed esterification and gamma-lactonizations were studied to test the sensitivity of a chemical reaction to the orientation of the reacting atoms. Variation in orientation of the attacking oxygen atom relative to the carbon atom of the carboxylic acid was achieved by using bicyclic ring systems to limit the conformational mobility of the gamma-hydroxy acids. Factors as high as 2 x 10(4) were observed for the acceleration of a reaction due to this "orientation factor" even after corrections for proximity and torsional strain have been made. The orientation factor is related to the shape of the electron orbitals and must have an angular preference far greater than previously estimated. Such sensitivity to orientation would provide factors large enough to explain the gap in our understanding of enzyme catalysis. It is suggested that the catalytic efficiency of enzymes depends on their ability not only to juxtapose the reacting atoms but also to "steer" their orbitals along a path which takes advantage of this strong directional preference.

Journal Article↗
PubMedDate not supplied

Enhanced hippocampal CA1 LTP but normal spatial learning in inositol 1,4,5-trisphosphate 3-kinase(A)-deficient mice.

To define the physiological role of IP(3)3-kinase(A) in vivo, we have generated a mouse strain with a null mutation of the IP(3)3-kinase(A) locus by gene targeting. Homozygous mutant mice were fully viable, fertile, apparently normal, and did not show any morphological anomaly in brain sections. In the mutant brain, the IP4 level was significantly decreased whereas the IP3 level did not change, demonstrating a major role of IP(3)3-kinase(A) in the generation of IP4. Nevertheless, no significant difference was detected in the hippocampal neuronal cells of the wild-type and the mutant mice in the kinetics of Ca2+ regulation after glutamate stimulation. Electrophysiological analyses carried out in hippocampal slices showed that the mutation significantly enhanced the LTP in the hippocampal CA1 region, but had no effect on the LTP in dentate gyrus (DG). No difference was noted, however, between the mutant and the wild-type mice in the Morris water maze task. Our results indicate that IP(3)3-kinase(A) may play an important role in the regulation of LTP in hippocampal CA1 region through the generation of IP4, but the enhanced LTP in the hippocampal CA1 does not affect spatial learning and memory.

Animals↗
PubMedDate not supplied

Expression of a neuromodulin-beta-galactosidase fusion protein in primary cultured neurons and its accumulation in growth cones.

Cultured embryonic neurons share a number of characteristic morphological and physiological properties with their counterparts in vivo. For example, differentiating hippocampal neurons in culture develop two distinct classes of processes that serve as dendrites and axons. It has also been shown that the microtubule organization and composition in axons differs from those in dendrites, which may contribute to differential transport of macromolecules into axons or dendrites. We have expressed a neuromodulin-beta-galactosidase fusion gene in cultured mesencephalic neurons in order to study the transport of the neurospecific protein neuromodulin into neurite growth cones. When beta-galactosidase alone was expressed in neurons, it was found in the cell bodies with diffuse neurite staining. In marked contrast, the neuromodulin-beta-galactosidase fusion protein was rapidly transported into neurites and was concentrated in the growth cones. This system may provide a useful model for studying the structural domain(s) of neuromodulin that are required for transport and accumulation of neuromodulin in the growth cones of neurons.

Animals↗