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Dipeptidyl peptidase II (DPPII) from bovine kidney cortex and lung was purified to the electrophoretically homogeneous state. The molecular and catalytic characteristics of the enzyme were determined. It was revealed that DPPII preparations possess adenosine deaminase (ADA) activity at all purification steps. For the first time, the ADA-binding ability of DPPII has been shown similar to the well-known ADA-binding enzyme, DPPIV. The dissociation constant of the DPPII-ADA complex was estimated using a resonant mirror biosensor (80 nM), fluorescence polarization (60 nM), and differential spectroscopy (36 nM) techniques. The data demonstrate that DPPII can form a complex with ADA, but with one order of magnitude higher dissociation constant than that of DPPIV (7.8 nM).

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The kinetic parameters of adenosine deaminase such as Km and Ki were determined in the absence and presence of adenine derivatives (R1-R24) in sodium phosphate buffer (50 mM; pH 7.5) solution at 27 degrees C. These kinetic parameters were used for QSAR analysis. As such, we found some theoretical descriptors to which the binding affinity of adenosine deaminase (ADA) towards several adenine nucleosides as inhibitors is correlated. QSAR analysis has revealed that binding affinity of the adenine nucleosides upon interaction with ADA depends on the molecular volume, dipole moment of the molecule, electric charge around the N1 atom, and the highest of positive charge for the related molecules.

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The interaction of adenosine deaminase (adenosine aminohydrolase, ADA) from bovine spleen with inhibitors--erythro-9-(2-hydroxy-3-nonyl)adenine, erythro-9-(2-hydroxy-3-nonyl)-3-deazaadenine, and 1-deazaadenosine--was investigated. Using selective chemical modification by diethyl pyrocarbonate (DEP), the possible involvement of His residues in this interaction was studied. The graphical method of Tsou indicates that of six His residues modified in the presence of DEP, only one is essential for ADA activity. Inactivation of the enzyme, though with low rate, in complex with any of the inhibitors suggests that the adenine moiety of the inhibitors (and consequently, of the substrate) does not bind with the essential His to prevent its modification. The absence of noticeable changes in the dissociation constants of any of the enzyme-inhibitor complexes for the DEP-modified and control enzyme indicates that at least the most available His residues modified in our experiments do not participate in binding the inhibitors--derivatives of adenosine or erythro-9-(2-hydroxy-3-nonyl)adenine.

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Adenosine deaminase from bovine cerebral hemisphere (white and gray matter) and spleen was treated with N-bromosuccinimide, a reagent known to oxidize selectively tryptophan residues in proteins. Spectrally observable tryptophan modification was accompanied by enzyme inactivation. Tsow graphics revealed that two Trps are essential for the activity of enzyme from both tissues. Enzyme inhibitors and substrate analogues, derivatives of erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) and adenosine, were able to protect Trp against modification, and this effect correlated in general with the enzyme activity protection. In the presence of adenosine deaza analogues (the noninhibitor tubercidin among them) only two Trps were modified in the fully inactivated enzyme. In the presence of EHNA and its deaza analogues, full inactivation of the enzyme was accompanied by the modification of four Trps. The obtained data confirm the previous hypothesis about the presence on the enzyme of different binding sites for adenosine and EHNA derivatives that are responsible for the different effects on the enzyme conformation elicited by the corresponding derivatives. Moreover, these data allow us to suggest that Trp residues, still unidentified by X-ray analysis, are essential for the functioning of the enzyme.

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INTRODUCTION: The number of works on investigation of crush syndrome (CS) pathogenesis, of organs and enzymatic systems at traumatic toxicosis is rather limited. While the clinical current of trauma and the lethality prognosis depend on a degree of violations in them. Such investigations are necessary for opportune diagnosis and definition of a treatment tactic. To complete this deficiency, adenylate deaminase (AMPD) level was studied in twelve tissues at experimental CS in vivo. RESULTS: The experimental model of CS on white rats was caused by crush and decompression of femoral muscle tissue. The CS influence on AMPD activity was investigated in hemisphere, cerebellum, hypothalamus, pituitary body, heart, lung, liver, spleen, kidney, adrenal, crushed and not crushed muscles. In muscles, kidney, pituitary body and adrenal the activity decreased in 2 hours crush but the compensation of effect is observed after 5 hours crush. In cerebellum, hemisphere, heart, liver and lung it decreased during both of crush times. After 2 and 5 hours crush in hypothalamus and in spleen AMPD activity appeared much higher than in control. After 2 hours crush at the end of 48 hours decompression, the activity in muscles, kidney, adrenal and pituitary body was lower, in cerebellum, hypothalamus, hemisphere and heart--higher than, in lung, spleen and liver--close to control. After 5 hours crush in the majority of studied tissues at the end of decompression, the activity was below of control. The greatest deviance was observed in muscles. As to brain in cerebellum and hemisphere the parameter was close to, in pituitary body and in hypothalamus it was 1,5-fold of control. CONCLUSION: AMPD level in the most of studied tissues differs from the control at definite time of crush and decompression. These results mean the possibility of nucleotides pool balance distortion and intermediates accumulation.

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INTRODUCTION: Publications on investigation of crush syndrome pathogenesis, particularly of enzymatic systems upon traumatic toxicosis are rather limited. Such investigations are necessary for opportune diagnosis and definition of a treatment tactic. To replenish this deficiency, the adenosine deaminase level was studied in 12 rat tissues at experimental crush syndrome in vivo. RESULTS: The experimental model of crush syndrome on white rats was induced by crush and decompression of femoral muscle tissue. The crush syndrome influence on activity of adenosine deaminase isoenzymes was investigated in hemisphere, cerebellum, hypothalamus, pituitary body, heart, lung, liver, spleen, kidney, adrenal, as well as in crushed and native muscles. In 2 and 5 hours after compression, the enzyme activity decreased in muscles, lung and heart; increased in hypothalamus; remains near the control value in kidney and spleen. In cerebellum the parameter practically does not vary during 2 hours compression, while increased in 5 hours. In adrenal, liver, pituitary body and hemisphere the data after 5 hours compression approximated the level of control value in account of compensating mechanism. In 48 hours decompression after 2 hours crush, the adenosine deaminase activity becomes higher than control value in hemisphere, hypothalamus, cerebellum, liver, heart, adrenal, intact muscle, lung and kidney; in the crushed muscle and spleen the activity is reduced down to 60% of control value. In 48 hours decompression after 5 hours compression, the enzyme activity is higher than control value in hypothalamus, pituitary body, hemisphere, cerebellum, kidney, adrenal, heart and lung. The activity is reduced in muscles, spleen and liver. CONCLUSION: The level of adenosine deaminase in most of studied tissues differs from the control value depending on compression and decompression time. It is worthy of note that namely during decompression, the enzyme level deviates from the control in the majority of tissues.

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The incubation of adrenal ferredoxin with various detergents in the presence of oxygen or ferricyanide leads to bleaching of the protein. The bleached preparation has the properties of apoferredoxin and it can be reconstituted with high yield by conventional methods.

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