Ornithine-δ-Transaminaseの精製およびその性質

概要

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Ornithine-δ-transaminase has been purified from rat liver mitochondria about 400 times active more than original mitochondria suspension using the technique of sonication, ammonium sulfate fractionation. heat treatment, DEAE-cellulose column chromatography and zone electrophoresis. The purified enzyme thus obtained is one component on ultracentrifugal pattern and electrophoresis. No activity of GOT and GPT was recognized. Supernatant fraction has not any activity. Sedimentation constant (S_<20>W) was 7.1×10^<-13> and molecular weight was approximately 115,000. It has been concluded that the enzyme is pyridoxal phosphate enzyme from the following data : i.e. the enzyme was strongly inhibited by vitamin B_6-enzyme inhibitors, such as INAH, thiosemicarbazide and hydroxylamine, and the resolved apoenzyme is able to recover its full activity by an addition of pyridoxal phosphate. The properties of the enzyme were as followes : (1) Km for ornithine 6.0×10^<-4>M, for α-ketoglutarate 8.45×10^<-4>M, and for pyridoxal phosphate 1.13×10^<-5>M. (2) Turnover number for α-ketoglutarate 63.66,for glyoxalate 12.02,for pyruvate 1.84,and for oxalacetate 0.46. (3) When oxalacetate was added to α-ketoglutarate-ornithine system, competitive inhibition between α-ketoglutarate and oxalacetate was recognized exactly.
日本ビタミン学会の論文
1963-02-25