TY - JOUR
T1 - Hydrolysis catalyzed with a resin containing histidine groups
AU - Hung, Wei Hsiu
AU - Hu, Cho Chun
AU - Liu, Chuen Ying
N1 - Funding Information:
We thank the National Science Council of the Republic of China for financial support.
PY - 1996/10/10
Y1 - 1996/10/10
N2 - A histidine-containing polymer was synthesized in which the amino group of the histidine was attached chemically via an azide coupling method to the carboxylic acid of Amberlite IRC-50. The resultant polymer was applied as a catalyst for hydrolysis of p-nitrophenyl acetate (PNPA). PNPA in aqueous solution was hydrolyzed at 25°C with a phosphate buffer (pH 7.8). The observed kinetics obey those of Michaelis-Menten. The reaction rates at various temperatures were measured. The activation parameters, pre- exponential factor (A) and activation energy (E(a)), were 6.64 x 10-4 min- 1 and 37.5 kJ mol-1 respectively. At a pH of the medium greater than 7.8, the reaction rate remained almost constant (k(obs) = 0.024 min-1) and seemed to be controlled by the rate of diffusion of PNPA from the bulk solution into the catalytically active site at the resin channel surface. For catalysed hydrolysis, the effect of ionic strength in solution demonstrated that bifunctional cooperation between adjacent histidine groups existed through the nucleophilicity of nitrogen. The effects of metal ions and aspartic acid or serine on hydrolysis were also investigated.
AB - A histidine-containing polymer was synthesized in which the amino group of the histidine was attached chemically via an azide coupling method to the carboxylic acid of Amberlite IRC-50. The resultant polymer was applied as a catalyst for hydrolysis of p-nitrophenyl acetate (PNPA). PNPA in aqueous solution was hydrolyzed at 25°C with a phosphate buffer (pH 7.8). The observed kinetics obey those of Michaelis-Menten. The reaction rates at various temperatures were measured. The activation parameters, pre- exponential factor (A) and activation energy (E(a)), were 6.64 x 10-4 min- 1 and 37.5 kJ mol-1 respectively. At a pH of the medium greater than 7.8, the reaction rate remained almost constant (k(obs) = 0.024 min-1) and seemed to be controlled by the rate of diffusion of PNPA from the bulk solution into the catalytically active site at the resin channel surface. For catalysed hydrolysis, the effect of ionic strength in solution demonstrated that bifunctional cooperation between adjacent histidine groups existed through the nucleophilicity of nitrogen. The effects of metal ions and aspartic acid or serine on hydrolysis were also investigated.
KW - Histidine-containing resin
KW - Hydrolysis
KW - p-Nitrophenyl acetate
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U2 - 10.1016/1381-1169(96)00031-3
DO - 10.1016/1381-1169(96)00031-3
M3 - Article
AN - SCOPUS:0030579199
SN - 1381-1169
VL - 112
SP - 1
EP - 7
JO - Journal of Molecular Catalysis A: Chemical
JF - Journal of Molecular Catalysis A: Chemical
IS - 1
ER -