ISSN:
1573-4943
Keywords:
ATP-AMP transphosphorylase
;
adenylate kinase
;
myokinase
;
nucleotide-binding peptides and peptide fragments
;
ligand binding
;
peptide synthesis
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Two peptide fragments, derived from the head and tail of rabbit muscle myokinase, were found to possess remarkable and specific ligand-binding properties (Hamadaet al., 1979). By initiating systematic syntheses and measurements of equilibrium substrate-binding properties of these two sets of peptides, or portions thereof, which encompass the binding sites for (a) the magnesium complexes of the nucleotide substrates (MgATP2− and MgADP−) and (b) the uncomplexed nucleotide substrates (ADP3− and AMP2−) of rabbit muscle myokinase, some of the requirements for binding of the substrates to ATP-AMP transphosphorylase are being deduced and chemically outlined. One requirement for tight nucleotide binding appears to be a minimum peptide length of 15–25 residues. In addition, Lys-172 and/or Lys-194 may be involved in the binding of εAMP. The syntheses are described as a set of peptides corresponding to residues 31–45, 20–45, 5–45, and 1–45, and a set of peptides corresponding to residues 178–192, 178–194, and 172–194 of rabbit muscle adenylate kinase. The ligand-binding properties of the first set of synthetic peptides to the fluorescent ligands: εMgATP/εATP and εMgADP/εADP are quantitatively presented in terms of their intrinsic dissociation constants (K′d) and values ofN (maximal number of moles bound per mole of peptide); and compared with the peptide fragment MT-I (1–44) obtained from rabbit muscle myokinase (Kubyet al., 1984) and with the native enzyme (Hamadaet al., 1979). In addition, the values ofN andK′d are given for the second set of synthetic peptides to the fluorescent ligands εAMP and εADP as well as for the peptide fragments MT-XII(172–194) and CB-VI(126–194) (Kuby et al., 1984) and, in turn, compared with the native enzyme. A few miscellaneous dissociation constants which had been derived kinetically are also given for comparison (e.g., theK i for εAMP and the value of $$\bar K_{Mg\varepsilon ATP} $$ obtained for the native enzyme) (Hamada and Kuby, 1978), and theK'd measured for Cr3+ and the synthetic peptide I1–45 (Fryet al., 1985b).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01026438
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