[Comparative evaluation of biological availability of 137Cs in soil of various types of forest ecosystems]. / Sravnitel'naia otsenka biologicheskoi dostupnosti 137Cs v pochvakh lesnykh ékosistem razlichnogo tipa.

On five forests plots varying in species composition of woody plants and soil properties, 137Cs vertical distribution and 137Cs forms occurring in different horizons of forest soils have been studied. It was found that bulk 137Cs and contents of physico-chemical forms of this radionuclide in different horizons of forest soils vary considerably within both plots with different characteristics and individual horizons. The reported regularities can explain observed differences in 137Cs distribution in forest ecosystems of various types.

[Analysis of factors determining the biological availability of 137Cs in forest ecosystem soils]. / Analiz faktorov, opredeliaiushchikh biologicheskuiu dostupnost' 137Cs v pochvakh lesnykh ékosistem.

On five forest plots varying in species composition of woody plants and soil properties, 137Cs accumulation by vegetation of the forest understorey has been studied. Differences in 137Cs availability for root uptake are shown to be dependent on a vertical distribution of 137Cs content over the soil profile, percentage of exchangeable 137Cs and distribution of plant root systems (fungous mycelium) in soil. A 137Cs-bioavailability index is suggested and its non-linear relationship with 137Cs transfer factors to different plant species in the understorey is shown.

Isolation of human liver angiotensin-converting enzyme by chromatofocusing.

Angiotensin-converting enzyme (EC 3.4.15.1) has been isolated from human liver by chromatofocusing. The isolation procedure permitted us to obtain a 9000-fold purified enzyme with a 22% yield. Specific activity of the angiotensin-converting enzyme was 10 units/mg of protein. The molecular mass of enzyme determined by polyacrylamide gel electrophoresis under denaturing conditions was 150,000. The isoelectric point (4.2-4.3) was also determined by chromatofocusing. The Km values of the enzyme for hippuryl-L-histidyl-L-leucine and N-benzyloxycarbonyl-L-phenylalanyl-L-histidyl-L-leucine are 5000 and 125 microM, respectively. The human liver angiotensin-converting enzyme is inhibited by bradykinin-potentiating factor SQ 20881 (IC50 = 18 nM).

[Purification and study of the physicochemical properties of angiotensin converting enzyme from the human liver]. / Ochistka i issledovanie fiziko-khimicheskikh svoistv angiotenzinprevrashchaiushchego fermenta iz pecheni cheloveka.

Angiotensin-converting enzyme (ACE) from human liver was first purified 9000-fold by chromatofocusing with 22% yield. The enzyme had a specific activity of 10 U/mg. The enzyme molecular weight was 150000, as determined by electrophoresis in a 7.5% polyacrylamide gel. The enzyme pI determined by chromatofocusing was 4.2-4.3. KM of human liver ACE, measured using hippuryl-L-histidyl-L-leucine and N-benzyloxycarbonyl-L-phenylalanyl-L-histidyl-L-leucine as substrates, was 5 mM and 0.1 mM, respectively. Human liver ACE was inhibited by SQ 20881 with IC50 equal to 1.8 X 10(-8) M.