Diverse effects of poly-basic amino acids, heparin and ionic strength on the phosphorylation of various substrates by cytosolic protein-tyrosine kinase from porcine spleen.
1. Effects of poly-basic amino acids, heparin and ionic strength on the activity of cytosolic protein-tyrosine kinase from porcine spleen (CPTK-40) have been studied. 2. Both polylysine and polyarginine stimulated the phosphorylation of [Val5]angiotensin II and E11 G1 (synthetic peptide of EDAEYAARRRG), but could neither stimulate nor inhibit the phosphorylation of random copolymers; poly(EY)4:1 and poly(EAY)6:3:1. 3. Heparin stimulated the phosphorylation of poly(EY)4:1 by 2.5-fold, however, it inhibited those of E11G1, poly(EAY)6:3:1, casein and H2B histone. 4. Elevation of ionic strength of either NaCl, KCl or (NH4)2SO4 stimulated the phosphorylation of poly(EY)4:1 by greater than 5-fold, but inhibited those of casein, tubulin, H2B histone, E11G1 and poly(EAY)6:3:1. 5. These effectors did not change the Km for substrates but increased the Vmax. 6. These results suggest that the effects of poly-basic amino acids, heparin and ionic strength on the activity of CPTK-40 are mainly on the substrates employed rather than on the enzyme itself.
Asahi
M
M
Department of Biochemistry, Fukui Medical School, Japan.
Taniguchi
T
T
Sakai
K
K
Nakamura
S
S
Yamamura
H
H
D000596:Amino Acids / Q000494:pharmacology*; D000818:Animals; D002474:Cell-Free System; D006493:Heparin / Q000494:pharmacology*; D009994:Osmolar Concentration; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000302:isolation & purification / Q000378:metabolism*; D013154:Spleen / Q000201:enzymology*; D013552:Swine
D000596:Amino Acids; D006493:Heparin; D011505:Protein-Tyrosine Kinases