Rönnstrand L, Sorokin A, Engström U, Heldin C H
Ludwig Institute for Cancer Research, Biomedicum, Uppsala, Sweden.
Biochem Biophys Res Commun. 1990 Mar 30;167(3):1333-40. doi: 10.1016/0006-291x(90)90669-e.
Synthetic peptides derived from the sequence surrounding tyrosine-857 in the human platelet-derived growth factor (PDGF) beta-receptor were used to elucidate the requirement for length and presence of negative and positively charged amino acids in substrates of the PDGF beta-receptor protein tyrosine kinase. The measured Km for the different peptides were all in the range 1-10 mM. A peptide of only five amino acids, lacking acidic amino acid residues, were found to be substrates for the receptor kinase. Ligand binding was found to stimulate the phosphorylation of peptides mainly by lowering the Km both for peptide and for ATP. Only minor changes in the Vmax occurred upon stimulation with PDGF. The reaction mechanism was found to be sequential, i.e. both the peptide and ATP have to bind to the enzyme before any product is released.
源自人血小板衍生生长因子（PDGF）β受体中酪氨酸 - 857周围序列的合成肽被用于阐明PDGFβ受体蛋白酪氨酸激酶底物中负电荷和正电荷氨基酸的长度要求和存在情况。不同肽的测得Km值均在1 - 10 mM范围内。发现一种仅含五个氨基酸且缺乏酸性氨基酸残基的肽是受体激酶的底物。发现配体结合主要通过降低肽和ATP的Km来刺激肽的磷酸化。用PDGF刺激后，Vmax仅发生微小变化。发现反应机制是顺序性的，即肽和ATP都必须在任何产物释放之前与酶结合。
