Abstract
A bifunctional polymer catalyst was prepared by radical polymerization of benzyl N-methylacrylohydroxamate and 4-vinylimidazole, followed by the removal of the benzyl group, and the hydrolysis of four phenyl ester substrates was examined in 28.9 vol/vol % EtOH-H2O at 30 °C. The Michaelis-Menten kinetics were observed only for a long-chain, anionic substrate. The major course of catalysis was acylation and deacylation at the hydroxamate group. The acylation process consisted of the simple nucleophilic attack of the hydroxamate anion (kA- ) and the general base (imidazole) catalyzed nucleophilic attack of the hydroxamic acid (kHA)· In the case of p-nitrophenyl acetate (PNPA), KHA and kA-were 0.50 and 36 M-1 s-1, respectively, and the difference was much smaller for other substrates. The deacylation reaction proceeded efficiently due to the general-base catalysis of the imidazole group. Thus, the imidazole group acts as a general base in both the acylation and deacylation process, in close resemblance to the charge relay system of serine proteases.
| Original language | English |
|---|---|
| Pages (from-to) | 7793-7799 |
| Number of pages | 7 |
| Journal | Journal of the American Chemical Society |
| Volume | 98 |
| Issue number | 24 |
| DOIs | |
| Publication status | Published - Nov 1 1976 |
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All Science Journal Classification (ASJC) codes
- Catalysis
- Chemistry(all)
- Biochemistry
- Colloid and Surface Chemistry
Cite this
Multifunctional Hydrolytic Catalyses. 7. Cooperative Catalysis of the Hydrolysis of Phenyl Esters by a Copolymer of N-Methylacrylohydroxamic Acid and 4-Vinylimidazole. / Kunitake, Toyoki; Okahata, Yoshio.
In: Journal of the American Chemical Society, Vol. 98, No. 24, 01.11.1976, p. 7793-7799.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Multifunctional Hydrolytic Catalyses. 7. Cooperative Catalysis of the Hydrolysis of Phenyl Esters by a Copolymer of N-Methylacrylohydroxamic Acid and 4-Vinylimidazole
AU - Kunitake, Toyoki
AU - Okahata, Yoshio
PY - 1976/11/1
Y1 - 1976/11/1
N2 - A bifunctional polymer catalyst was prepared by radical polymerization of benzyl N-methylacrylohydroxamate and 4-vinylimidazole, followed by the removal of the benzyl group, and the hydrolysis of four phenyl ester substrates was examined in 28.9 vol/vol % EtOH-H2O at 30 °C. The Michaelis-Menten kinetics were observed only for a long-chain, anionic substrate. The major course of catalysis was acylation and deacylation at the hydroxamate group. The acylation process consisted of the simple nucleophilic attack of the hydroxamate anion (kA- ) and the general base (imidazole) catalyzed nucleophilic attack of the hydroxamic acid (kHA)· In the case of p-nitrophenyl acetate (PNPA), KHA and kA-were 0.50 and 36 M-1 s-1, respectively, and the difference was much smaller for other substrates. The deacylation reaction proceeded efficiently due to the general-base catalysis of the imidazole group. Thus, the imidazole group acts as a general base in both the acylation and deacylation process, in close resemblance to the charge relay system of serine proteases.
AB - A bifunctional polymer catalyst was prepared by radical polymerization of benzyl N-methylacrylohydroxamate and 4-vinylimidazole, followed by the removal of the benzyl group, and the hydrolysis of four phenyl ester substrates was examined in 28.9 vol/vol % EtOH-H2O at 30 °C. The Michaelis-Menten kinetics were observed only for a long-chain, anionic substrate. The major course of catalysis was acylation and deacylation at the hydroxamate group. The acylation process consisted of the simple nucleophilic attack of the hydroxamate anion (kA- ) and the general base (imidazole) catalyzed nucleophilic attack of the hydroxamic acid (kHA)· In the case of p-nitrophenyl acetate (PNPA), KHA and kA-were 0.50 and 36 M-1 s-1, respectively, and the difference was much smaller for other substrates. The deacylation reaction proceeded efficiently due to the general-base catalysis of the imidazole group. Thus, the imidazole group acts as a general base in both the acylation and deacylation process, in close resemblance to the charge relay system of serine proteases.
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UR - http://www.scopus.com/inward/citedby.url?scp=0011775687&partnerID=8YFLogxK
U2 - 10.1021/ja00440a054
DO - 10.1021/ja00440a054
M3 - Article
AN - SCOPUS:0011775687
VL - 98
SP - 7793
EP - 7799
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 24
ER -