Study On The Parallel Catalytic Hydrogen Wave Of Protein

At present, the electrochemical studies on protein have been mainly concerned with its reduction wave, parallel catalytic wave and catalytic hydrogen wave. The polarographic reduction wave of protein is resulted from the reversible reduction of disulfate linkage. When oxidant such as potassium iodate is present, sulfhydryl, the intermediate products of reduction of disulfate linkage, can be oxidized to regenerate disulfate linkage, producing the parallel catalytic wave of protein.The polarographic catalytic hydrogen wave of protein can be classified into two types. One is the pre-sodium wave. The other is the catalytic hydrogen wave of complexes of protein with metal ions. In this thesis, we studied the new kinetic wave of protein (bovine serum albumin, lysozyme, papain, human serum albumin and diphtheria toxoid), resulted from the pre-sodium catalytic hydrogen wave when it was catalyzed by oxidant such as potassium iodate, potassium persulfate and hydrogen peroxidate further, and discussed the mechanism of this new kinetic wave. This kinetic wave based on catalytic hydrogen wave was a new type of polarographic catalytic wave of protein, which has never been reported in previous literature. Thus, it is suggested to name this new kinetic wave as the parallel catalytic hydrogen wave. This thesis includes six parts. Chapter I The achievement on electrochemistry of protein was reviewed. Chapter n In NH^Cl-NHa'HaO (pH8.31) buffer solution, bovine serum albumin (BSA) yielded a polarographic catalytic hydrogen wave with peak potential -1.80V (vs. SCE). When certain amount of oxidant such as potassium iodate, potassium persulfate and hydrogen peroxidate were present, a new kinetic wave appeared. Studies indicated the new kinetic wave was the parallel catalytic hydrogen wave of BSA, and the parallel catalytic hydrogen wave was used as a new method to improve the analytical sensitivity of trace BSA.Chapter III In 0.4 mol/L NH4C1- NH3H2O (pH8.31) buffer solution, the catalytic hydrogen wave of lysozyme (LE), with the peak potential -1.80V (vs. SCE), was catalyzed further by KIOs, producing a parallel catalytic hydrogen wave. The parallel catalytic hydrogen wave gives a convenient approach for the study on the oxidation reaction kinetic of atomic hydrogen by oxidant, and the apparent rateconstant of oxidation of atomic hydrogen by IO3~was determined to be 1.86 X 104 L moL-1 s-1.Chapter IV Papain (PAP) yielded a polarographic catalytic hydrogen wave with the peak potential -1.87V (vs. SCE), in 0.4 mol/L NHjCl- NH3 H2O (pH 8.31) buffer solution. When KIO3 was present, the catalytic hydrogen was catalyzed further, producing a new kinetic wave. The mechanism of this new kinetic wave was discussed, and the apparent rate constant of oxidation of atomic hydrogen by IO3-was determined to be 2.35X 104 L moL"1 s"1, Meanwhile, a new method was established to determine trace PAP.Chapter V A new kinetic wave, termed as parallel catalytic hydrogen wave, of human serum albumin (HSA) in the presence of potassium persulfate was reported. In 0.4 mol/L NH4C1- NH3'H2O (pH 8.58)-0.01 mol/L K2S2Og supporting electrolyte, HSA yielded a parallel catalytic hydrogen wave with peak potential of -1.85V (vs. Ag/AgCl). The second-order derivative peak current of the parallel catalytic hydrogen wave was linearly proportional to HSA concentration in the range of 3.2 X 10"9~9.6X 10"9 mol/L. The parallel catalytic hydrogen wave was applied to the determination of HSA content in human serum and urine, with satisfactory results. Chapter VI Diphtheria toxoid (DT) yielded a polarographic catalytic hydrogen wave with the peak potential -1.89V (vs. SCE), in 0.4 mol/L NHUCl- NH3H2O (pH 8.31) buffer solution, and the catalytic hydrogen wave of DT was catalyzed by KIO3 further to produce a parallel catalytic hydrogen wave. In 0.04 mol/LNH3 H2O (pH 8.31)-5.0X 10"3 mol/L KIO3 medium, the second-order derivative peak current of the parallel catalytic wave of DT was proportional to its concentration in the range of 0.2-1.0 g/mL. The parallel catalytic...