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Biomedical subjects

H Kanazawa

Publications and source records attributed to H Kanazawa.

At least 307 records · Page 17Linked to original sources
PubMed1982

Hybrid ATPase's formed from subunits of coupling factor F1's of Escherichia coli and thermophilic bacterium PS3.

ATPase complexes were reconstituted from homologous and heterologous combinations of alpha, beta, and gamma subunits of coupling factor ATPase TF1 of thermophilic bacterium PS3 and EF1 of Escherichia coli. TF1 and alpha beta gamma complex reconstituted from TF1 subunits were thermostable and activated by methanol, sodium dodecyl sulfate and anions and they were halophilic, whereas EF1 and its three-subunit complex did not show these properties. The hybrid ATPase alpha T beta T gamma E (complex of the alpha and beta subunits of TF1 and the gamma subunit of EF1) showed closely similar properties to TF1 except for thermostability, while alpha E beta E gamma T (alpha and beta from EF1 and gamma from TF1) had similar properties to EF1. These results suggest that alpha and/or beta is required for the properties of F1. The complex alpha E beta T gamma E showed similar properties to EF1 except for its optimum pH: this complex had a broad pH optimum at about pH 7, whereas EF1 had an optimum at pH 8.5. No hybrid complexes were thermostable, suggesting that all three subunits of TF1 are required for heat stability. These hybrids showed higher halophilicity than EF1, although they were less halophilic than TF1. The hybrid enzymes studied here are the first thermophilic-mesophilic hybrid enzymes obtained.

Adenosine Triphosphatases↗
PubMed1982

Structure and function of H+-ATPase: what we have learned from Escherichia coli H+-ATPase.

We have identified a transducing phage lambda asn5 carrying a set of structure genes coding for F1F0. New transducing phages and plasmids carrying a part of the DNA fragment in lambda asn5 were isolated and assayed by genetic complementation with mutants of F1F0. After analysis of DNA from these phages and plasmids, we mapped the genes for F1F0 within a physically defined segment of DNA of 4.5 megadaltons. The nucleotide sequence of the DNA segment was determined, and the primary amino acid sequences of all the subunits were determined. We discuss the homology of the sequence with those of other proteins capable of nucleotide binding. The secondary structures of the subunits were deduced, and a Rossman fold was found in the beta-subunit. The b- and delta-subunits had unique secondary structures. The roles of the subunits of F1 were studied by analysis of isolated subunits and mutationally altered subunits. Conformational changes of the alpha- and beta-subunits and transmission of conformational change between the two subunits were observed. Intracistronic mapping of mutations was achieved.

Adenosine Triphosphatases↗
PubMed1981

Role of inducer exclusion in preferential utilization of glucose over melibiose in diauxic growth of Escherichia coli.

The role of inducer exclusion in diauxic growth of Escherichia coli on glucose and melibiose was investigated. The amounts of glucose and melibiose in the culture medium were determined during the diauxie. Glucose was consumed during the first growth cycle of the diauxie, and melibiose was consumed during the second cycle. The addition of adenosine 3',5'-cyclic monophosphate to the culture medium released both transient and catabolite repressions on the melibiose operon by glucose. Biphasic growth without a transient lag phase was observed in the presence of adenosine 3',5'-cyclic monophosphate. Preferential utilization of glucose over melibiose was observed even under such conditions. Thus, it is clear that inducer exclusion alone is sufficient to ensure the preferential utilization of glucose over melibiose. Similar results were obtained from a glucose-lactose diauxie. Inducer exclusion itself was not affected by adenosine 3',5'-cyclic monophosphate.

Biological Transport↗