The interaction between monoammonium glycyrrhizinate (MAG) and bovine serum albumin (BSA) were studied by fluorescence and absorption spectroscopy. The quenching mechanism of fluorescence of bovine serum albumin by monoammonium glycyrrhizinate was discussed. The binding sites number n and apparent binding constant K were measured by fluorescence quenching method. The thermodynamic parameters [1]H◦, [1]G◦, [1]S◦ at different temperatures were calculated. The distance r etween donor (bovine serum albumin) and acceptor (monoammonium glycyrrhizinate) was obtained according to F˝orster theory of non-radiation energy transfer. The results of synchronous fluorescence spectra and UV－vis absorption spectra show that the conformation of bovine serum albumin has been changed.

The water-soluble quaternary ammonium salt of chitosan was synthesized by reaction of chitosan with glycidyl trimethylammonium chloride. It was characterized by Fourier transform infrared and carbon-13 magnetic resonance spectra. Its microbiostatic effects against Staphylococcus aureus, Escherichia coli and Candid albicans were explored by microcalorimetry. The antimicrobial activity of the quaternized chitosan was stronger in alkaline condition than that in weak acidic condition.

An on-line solution-reaction isoperibol calorimeter has been constructed. The performance of the apparatus was evaluated by measuring the molar enthalpy of solution of KCl inwater at 298.15 K. The uncertainty and the inaccurary of the experimental results were within±0.3% compared with the recommended reference data. Using the calorimeter, the molar enthalpies of reaction for the following two reactions: LaCl3-7H2O(s)+2Hhq(s)+NaAc(s)=La(hq)2Ac(s)+NaCl(s)+2HCl(g)+7H2O(l) and PrCl3-6H2O(s)+2Hhq(s)+NaAc(s)= Pr(hq)2Ac(s)+NaCl(s)+2HCl(g)+6H2O(l), were determined at T=298.15 K, as−(78.3±0.6) and−(97.3±0.5) kJ mol−l, respectively. From the above molar enthalpies of reaction and other auxiliary thermodynamic quantities, the standard molar enthalpies of formation of La(hq)2Ac and Pr(hq)2Ac, at T=298.15 K, have been derived to be−(1535.5±0.7) and−(1536.7±0.6) kJ mol−l, respectively

The process that T4 phages multiply in host cells of Escherichia coli B was determined using LKB-2277 Bioactivity Monitor by means of stopped-flow method, and the growth was measured turbidometrically at the same time at 37 8C. By analyzing thermocurves, quantitative parameters could be obtained to characterize the interactions of host cells and phages. The parameters such as ka, Pmax, G etc. change regularly with the decrease of multiplicity of infection (MOI) value. Infection/lysis equations were fitted and the lytic rate constant kL was obtained. The results show that the metabolic activity of infected cells is more intensive than that of normal cells. The phenomenon of lysis inhibition (LIN) was first detected with the microcalorimetric method, and the mechanism is discussed.

The effect of Na2SeO3 on the growth of Halobacterium halobium R1 was investigated by means of microcalorimetry at 37°C. The biological response to toxicants is observed as the inhibition of the rate constant of growth of living cells. A low concentration of Na2SeO3 stimulated the growth of H. halobium R1, and a high concentration of Na2SeO3 inhibited the growth of H. halobium R1. Toxicity may be expressed as the half-inhibition concentration (IC50). The rate constants of growth (k) and the concentrations of Na2SeO3 (c) shows a linear relationship: k=1.790×10-6-2.27×10-3c. The value of IC50 obtained from the accompanying figure of I-c is 679 μg/mL.