PubMed · 6016953
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I M Klotz. 1967-02-10. Protein subunits: a table.. https://doi.org/10.1126/science.155.3763.697
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Eighteen strains of P. maltophilia were screened for the occurrence of plasmid using four different methods. Five of them were harbor plasmids. The results of plasmid detection in different growth phase of P2 strain showed that the highest amount of plasmids in the strain was observed in stationary growth phase. The characteristics of plasmid of P. maltophilia P2 was investigated by methods of agarose gel electrophoresis, restriction endonucleases analysis, determination of molecular weight. The results indicated that P. maltophilia P2 contained only one type of plasmid, its molecular weight was 4.4 x 10(6) dalton and that the plasmid had single BamHI. PstI. XbaI EcoRI. HindIII sites. Thus, the plasmid of P. maltophilia P2 may be developed into a fine cloning vector.
Nucleoside-diphosphate kinase is an enzyme which catalyzes the phosphorylation of nucleoside diphosphates into the corresponding triphosphates for nucleic acid biosynthesis. In this communication, we describe the purification and characterization of nucleoside-diphosphate kinase from yeast. The purified protein appears to be homogeneous by sodium dodecyl sulfate-polyacrylamide gel analysis, with a molecular weight of about 17,000-18,000. An estimate from the fast protein liquid chromatography Superose 12 gel filtration shows a native molecular weight of about 68,000 to 70,000. The results suggest that yeast nucleoside-diphosphate kinase is composed of four subunits. Substrate specificity studies show that the relative activity of nucleoside diphosphates (NDP) as phosphate acceptors is in the order of dTDP greater than CDP greater than UDP greater than dUDP greater than GDP greater than or equal to dGDP greater than dCDP greater than dADP greater than ADP; and the relative activity of triphosphate donors is in the order of UTP greater than dTTP greater than CTP greater than dCTP greater than dATP greater than ATP greater than or equal to dGTP greater than GTP. The Km and Vm of dTDP, dGDP, dCDP, dUDP, CDP, and UDP have been determined. The rate constant studies indicate that the purified NDP kinase prefers using, to a slight extent, dTDP (approximately 800 min-1) as the substrate rather than other tested deoxyribo- and ribonucleotides (350-450 min-1). The broad substrate specificity and kinetic data suggest that the enzyme is involved in both DNA and RNA metabolism.
The accessible surface areas of 58 monomeric and dimeric proteins, when measured in the crystalline environment, are found to be simply related to molecular weight. The loss of accessible surface when the proteins go from a free to their crystalline environment is well defined, implying that the hydrophobic interaction, which has been found to contribute to protein folding and stability in living systems, also contributes to protein crystal stability.