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71.
Achim Recktenwald Karl-Heinz Kroner Maria-Regina Kula 《Enzyme and microbial technology》1985,7(12):607-612
Flow injection analysis (FIA) has been employed to automate enzyme assays for formate dehydrogenase (FDH) and l-leucine dehydrogenase (l-LeuDH). Coupled to a special sampling device the FIA assays were used to monitor on-line downstream processes, e.g. disintegration of microbial cells and cross-flow filtration of cell homogenates. 相似文献
72.
Summary Mitochondrial creatine kinase (CK) purified from canine myocardium showed a single protein band on SDS-PAGE and was free of
MMCK. Its amino acid composition was different than MMCK or BBCK and did not react to antiserum to MMCK or BBCK. Using purified
mitochondrial, MM and BBCK, the velocity of reaction (V) was estimated for creatine phosphate (CP), creatine (C), adenosine
triphosphate (ATP) and adenosine diphosphate (ADP) over a wide range of concentrations including those at Vmax. The values for Km (mM/L) derived from Lineweaver-Burke plots are shown:
The affinity of mitochondrial CK for C is much greater than MMCK which is compatible with the energy shuttle hypothesis, namely
ATP is converted by mitochondrial CK to CP, and then diffuses to the myofibril for conversion to ATP for utilization. 相似文献
73.
Restriction endonuclease EcoO109 from Escherichia coli H709c with heptanucleotide recognition site 5'-PuG/GNCCPy 总被引:1,自引:0,他引:1
A new restriction endonuclease, EcoO109, has been isolated from Escherichia coli H709c by polyethyleneimine (PEI) precipitation, DEAE-cellulose chromatography and heparin agarose chromatography. The yield was high, more than 3000 units/g of wet cells. The EcoO109 endonuclease recognizes and cleaves a nucleotide sequence of (formula: see text), in the presence of 10 mM Mg2+. The enzyme will be useful for structural analysis and molecular cloning of DNA because of the stability, high yield and easy handling of the producer strain. 相似文献
74.
J. Wiegel 《Archives of microbiology》1985,142(2):194-199
The -isopropylmalate synthase of the chemolithoautotrophic Alcaligenes eutrophus H16 is apparently a soluble enzyme but is strongly adsorbed to cell particles in ruptured cell suspensions. This was not observed with -acetohydroxy acid synthase or threonine deaminase. The formation of these regulatory enzymes of the branched chain amino acid biosynthesis pathway generally decreased with decreased growth rates. The addition of 5 mM valine plus isoleucine with and without 5 mM threonine caused a 6.6- and a 4-fold increase, respectively, in the formation of active -isopropylmalate synthase, but caused a strong decrease in the -actohydroxy acid synthase. The level of active -isopropylmalate synthase is apparently regulated by the level of leucine; whereas, the level of the -acetohydroxy acid synthase and threonine deaminase is influenced by the presence of several amino acids. A catabolic threonine deaminase was not encountered.Abbreviations IRS
-Isopropylamalate
- AHA
-acetohydroxy acid
- TDA
throninedeaminase
This paper is dedicated to Professor H. G. Schlegel, University Göttingen, on the occasion of his 60th birthday. I am grateful to a great teacher and scientist, who in his unique way stimulated enthusiasm and fascination in microbiology in his students throughout the years 相似文献
75.
76.
Electromagnetic fields of very low amplitude have been reported to influence a number of cellular functions. Many of these
effects have a high degree of frequency specificity. Herein it is suggested that some of these reported results could be explained
by a fieldinduced alteration in the enzymic activity of integral membrane proteins. It is shown that such a field-induced
transition from an initial nonequilibrium steady-state to a final nonequilibrium steady-state can lead to an alteration in
the concentration profiles of those charged species in the cell's ambient electrolyte that comprise the so-called electrical
double layer. Examples of variations in the concentration profiles of those ions that react with a membrane-bound enzyme,
as well as nonreacting ionic species, are given. The modulation of such effects by systematic variations in extracellular
pH and ionic strength is discussed. 相似文献
77.
Kawalek J. C., Rew R. S. and Heavner J. 1984. Glutathione-S-transferase, a possible drug-metabolizing enzyme in Haemonchus contortus: comparative activity of a cambendazole-resistant and a susceptible strain. International Journal for Parasitology14: 173–175. A drug metabolizing enzyme (DME), glutathione-S-transferase, was detected in homogenates of a cambendazole-susceptible and a cambendazole-resistant strain of Haemonchus contortus. The activity was 1.5–1.8 times higher in the resistant strain. DME activation is a possible mechanism for anthelmintic resistance in H. contortus. 相似文献
78.
79.
80.
Irene Carlberg Kenneth Söderhäll Kristina Glimelius Tage Eriksson 《Physiologia plantarum》1984,62(3):458-464
Embryogenic and non-embryogenic cell strains of Daucus carota L. were examined for their protease activity using a wide range of chromogenic synthetic peptides as substrates. High arginine-specific activity was present in all strains, but no protease activity "specific" for embryogenic or non-embryogenic strains could be detected with the substrates tested. The specific protease activity was 5–10 times higher in the non-embryogenic as compared to the embryogenic strain for most tested substrates, and this difference was not due to release of proteases in the latter. All strains showed a decrease in protease activity when cultured in media without 2,4-dichlorophenoxyacetic acid, but the embryos had high protease activity in comparison with the nondifferentiated cell aggregates. In the latter aggregates, hydrolyzing activity towards three of the substrates (H-D-Phe-Pip-Arg- p -nitroanilide, Suc-Ala-Pro-Phe- p -nitro-anilide and Bz-Phe-Val-Arg- p -nitroanilide) was absent, whereas the embryos were able to hydrolyze them. 相似文献