Inactivation kinetics of polyphenol oxidase from pupae of blowfly (Sarcophaga bullata) in the dimethyl sulfoxide solution.
The effects of dimethyl sulfoxide (DMSO) on the activity of polyphenol oxidase (PPO, EC 1.14.18.1) from blowfly pupae for the oxidation of L-3,4-dihydroxyphenylalanine were studied. The results showed that low concentrations of DMSO could lead to reversible inactivation to the enzyme. The IC(50) value, the inactivator concentration leading to 50% activity lost, was estimated to be 2.35 M. Inactivation of the enzyme by DMSO was classified as mixed type. The kinetics of inactivation of PPO from blowfly pupae in the low concentrations of DMSO solution was studied using the kinetic method of the substrate reaction. The rate constants of inactivation were determined. The results show that k(+0) was much larger than k'(+0), indicating that the free enzyme molecule was more fragile than the enzyme-substrate complex in the DMSO solution. It was suggested that the presence of the substrate offers marked protection of this enzyme against inactivation by DMSO.
Chen
Chao-Qi
CQ
College of Urban and Environmental Sciences, Peking University, Peking 100871, China.
Li
Zhi-Cong
ZC
Pan
Zhi-Zhen
ZZ
Zhu
Yu-Jing
YJ
Yan
Ruo-Rong
RR
Wang
Qin
Q
Yan
Jiang-Hua
JH
Chen
Qing-Xi
QX
D000818:Animals; D004156:Catechol Oxidase / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism*; D004295:Dihydroxyphenylalanine / Q000737:chemistry; D004121:Dimethyl Sulfoxide / Q000737:chemistry / Q000494:pharmacology*; D004175:Diptera / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects; D007700:Kinetics; D010084:Oxidation-Reduction / Q000187:drug effects; D011679:Pupa / Q000201:enzymology; D012996:Solutions; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
D012996:Solutions; D004295:Dihydroxyphenylalanine; D004156:Catechol Oxidase; D004121:Dimethyl Sulfoxide