-transparent.png){kind=logo}
A unique phosphatase that selectively hydrolyzed phosphotyrosine and 2'-AMP at alkaline pH and p-nitrophenylphosphate at neutral pH was isolated from a cytosolic fraction of rat brain. The purified enzyme appeared homogenous on SDS-polyacrylamide gel electrophoresis and its molecular weight was estimated to be 42,000. The molecular weight of the native enzyme was 45,000 as determined by molecular sieve chromatography. These findings indicate that the native enzyme is a monomer protein. At pH 8.6, the enzyme hydrolyzed L-phosphotyrosine, D-phosphotyrosine, 2'-AMP, p-nitrophenylphosphate, 3'-AMP, 2'-GMP, and 3'-GMP; the ratio of its activities with these substrates was 100:96:115:68:39:25:16. Its Km values for L-phosphotyrosine, 2'-AMP, and p-nitrophenylphosphate were 0.8 X 10(-4) M, 1.4 X 10(-4) M, and 1.7 X 10(-4) M, respectively. At pH 7.4, the enzyme hydrolyzed p-nitrophenylphosphate, L-phosphotyrosine, and D-phosphotyrosine; the ratio of its activities with these compounds was 100:17:17, and its Km values for L-phosphotyrosine and p-nitrophenylphosphate were 1.8 X 10(-4) M and 2.0 X 10(-4) M, respectively. The enzyme activity was dependent on Mn2+ or Mg2+, and was strongly inhibited by 5'-nucleotides, pyrophosphate, and Zn2+. The enzyme was not sensitive to inhibitors of some well-characterized phosphatases such as NaF, molybdate, L(+)tartrate, tetramisole, vanadate, and lithium salt. The physiological role of the enzyme is discussed with respect to its activities toward phosphotyrosine, 2'-AMP, and p-nitrophenylphosphate.
N Motoyama, and
K Takimoto, and
M Okada, and
H Nakagawa
October 1986,
The Biochemical journal,
N Motoyama, and
K Takimoto, and
M Okada, and
H Nakagawa
September 1965,
Clinical chemistry,
N Motoyama, and
K Takimoto, and
M Okada, and
H Nakagawa
January 1970,
Acta histochemica,
N Motoyama, and
K Takimoto, and
M Okada, and
H Nakagawa
September 1965,
Clinical chemistry,
N Motoyama, and
K Takimoto, and
M Okada, and
H Nakagawa
May 1964,
Mie medical journal,
N Motoyama, and
K Takimoto, and
M Okada, and
H Nakagawa
January 1970,
Bratislavske lekarske listy,
N Motoyama, and
K Takimoto, and
M Okada, and
H Nakagawa
July 1947,
American journal of clinical pathology,
N Motoyama, and
K Takimoto, and
M Okada, and
H Nakagawa
August 1981,
FEBS letters,
N Motoyama, and
K Takimoto, and
M Okada, and
H Nakagawa
January 1951,
Acta physiologica et pharmacologica Neerlandica,
N Motoyama, and
K Takimoto, and
M Okada, and
H Nakagawa
August 1990,
Clinical chemistry,
