The enthalpies of solution in water of L--methionine and its zinc complexes Zn(Met)Cl2, Zn(Met)2Cl2·2H2O, Zn(Met)(NO3)2·1/2H2O, Zn(Met)3(NO3)2·H2O and Zn(Met)SO4·H2O have been measured at 298.15 K. The standard enthalpy of formation of met(aq) has been calculated. The experimental results have been discussed.
Authors:S. Chen, X. Yang, Sh. Gao, R. Hu, and Q. Shi
The solid complexes of Cr(NO3)3 with L-α-amino acids (AA=Val, Leu, Thr, Arg, Phe and Try) have been prepared in 95% alcoholic, the compositions of which were identified as the general
formula Cr(AA)2(NO3)32H2O by elemental and chemical analyses. The bonding characteristics of the title complexes were characterized by IR, indicating
that nitrogen and oxygen atoms in the ligands coordinated to Cr3+ in a bidentate fashion. With the aid of TG-DTG and IR techniques, the complexes were subjected to thermal decomposition in
an atmosphere of oxygen, presuming that the decompositions of the complexes consist of two steps and the complexes were decomposed
into chromium hemitrioxide after undergoing dehydration and skeleton splitting of the complexes. The constant volume energies
of combustion of the complexes were determined by a RBC-P type rotating-bomb calorimeter. According to Hess's law, the standard
enthalpies of formation of the complexes were calculated as (-1831.404.40), (-2542.036.13), (-1723.813.99), (-2224.313.02),
(-2911.616.53) and (-659.327.42) kJ mol-1, respectively.
Authors:S. Chen, Sh Gao, X. Yang, R. Hu, and Q. Shi
Solid complexes of M(His)2Cl2nH2O (M=Mn, Co, Ni, Cu) of MnCl26H2O, CoCl26H2O, NiCl26H2O, CuCl22H2O and L-α-histidine (His) have been prepared in 95% ethanol solution and characterized by elemental analyses, chemical analyses,
IR and TG-DTG. The constant-volume combustion energies of the complexes have been determined by a rotating-bomb calorimeter.
And the standard enthalpies of formation of the complexes have been calculated as well.
Authors:M. Lu, B. Wang, Zh. Li, Y. Fei, L. Wei, and Sh. Gao
Antifreeze protein (AFP) can lower the freezing point by inhibiting the growth of ice crystals. In this article, the thermal
hysteresis activity (THA) of a plant AFP was measured with differential scanning calorimetry (DSC). As is shown, when the
amount of ice in the sample was less than 5% THA of this AFP reached as high as 0.35°C. The secondary structure of this AFP
was studied with circular dichroism (CD). The CD spectrum from 195to 240 nm indicated a well-defined secondary structure consisting
11% α-helix, 34%antiparallel β-sheet and 55% random coil.