Interaction of Divalent Metal Ions with the Adenosine Triphosphate Measured Using Nuclear Magnetic Resonance

WTFZ] The interaction of adenosine triphosphate with divalent metal ions is important in biochemical functions. The effects of pH and metal ions Mg 2+ , Ca 2+ , Zn 2+ , Mn 2+ , and Co 2+ on the chemical shift of the phosphate group of ATP have been studied using Nuclear Magnetic Resonance. The chemical shift of the β-phosphate of ATP is the most sensitive to pH. Ca 2+ and Mg 2+ bind with the α- and β-phosphate groups of ATP. Zn 2+ binds to the adenosine ring hydrogen as well as to phosphate. The paramagnetic ions Mn 2+ and Co 2+ do not cause chemical shifts of the phosphate or proton peak. Mn 2+ and Co 2+ broaden the resonance peak only.[

Isolation and Biochemical Characteristics Analyses of Phenoloxidases (POs) in Three Cultured Mollusk Species

Phenoloxidases(POs)are a group of copper proteins including tyrosinase,catecholase and laccase,which play crucial roles in the innate immune response of mollusks.In this research,POs were studied in cultured mollusk species,including scallop Chla-mys farreri,abalone Haliotis discus hannai and clam Scapharca subcrenata.The POs were isolated from hemocytes using linear-gradient native-PAGE combined with catechol staining.The PO activities and their characters were investigated.The molecular mass of PO in C.farreri was 576 kDa,and it was 228 kDa in H.discus hannai.In S.subcrenata,four POs were detected and their mole-cular masses were 391 kDa,206 kDa,174 kDa and<67 kDa,which were named as 391-PO,206-PO,174-PO and s-PO,respectively.Ki-netic analyses indicated that all of the POs,except for 391-PO had higher affinity to L-DOPA and catechol than to hydroquinone and dopamine.However,all of the POs failed to oxidize tyrosine.The effects of divalent metal ions on POs’activities were assayed,in-cluding Fe^(2+),Mg^(2+),Zn^(2+),Mn^(2+),Cu^(2+)and Ca^(2+)from FeCl_(2),MgSO_(4),ZnSO_(4),MnCl_(2),CuSO_(4)and CaCl_(2).The POs were inhibited by Fe^(2+)at all determined concentrations.Additionally,the inhibition assay showed that all of the POs were inhibited by cysteine,ascorbic acid,sodium sulfite,citric acid,ethylenediaminetetraacetic acid disodium(EDTA)and sodium diethyldithiocarbamate(DETC).The inhibition effects of critric acid and EDTA are dose-dependent.H.discus hannai PO and 391-PO were slightly inhibited by sodium azide,and H.discus hannai PO,391-PO and 174-PO were slightly inhibited by thiourea.In conclusion,the POs in the three cultured mollusks are copper-containing laccase-type phenoloxidases with similar biochemical characteristics even though their molecular masses are different.

Thermal Behavior of Sr（ll） and Ba（ll）-Diclofenac Complexes in Solid State： Study of the Dehydration and Thermal Decomposition

Solid state compounds of general formula Sr（Diclof）2 ·5.7H2O and Ba（Diclof）2·4.8H2O were obtained. Thermo- gravimetry （TG）, differential scanning calorimetry （DSC）, X-ray diffraction powder patterns and microscopy analysis were used to characterize these compounds. Details concerning the dehydration and thermal decomposition as well as data of kinetic parameters have been described here. The kinetic behaviors of these stages were evaluated from several heating rates with samples masses of 2 and 5 mg in open crucibles under a nitrogen atmosphere. The results of the present study improve the knowledge on these compounds including their dehydration and thermal stability. The obtained data depend on the mass of the sample which results in two kinetic behavior patterns.