Preparation and properties of selected Zn(II)-peptide complexes in suspension.
The preparation and properties of low soluble, suspended Zn(II) complexes containing the selected peptides: tyroliberin (TRH), gonadorelin (GnRH), dalarelin and corticothropin (ACTH) were studied. The amount of Zn(II) bound by 1 muM of the selected peptide (n) was defined, as well as affinity of Zn(II) to the peptide (Ka) and the durability of the created complex Zn(II)-peptide (Kd). ACTH associated the highest amount of Zn(II), and GnRH the lowest one: 1 microM of ACTH complexed 0.81 microM +/- 0.03 Zn(II), the same quantity of GnRH-0.52 microM +/- 0.07 and TRH and dalarelin associated 0.75+/-0.03 and 0.79+/-0.02 microM of Zn(II), respectively. The closest affinity was stated between Zn(II) and GnRH (Ka=157.692+/-21.300 microM(-1)), the smallest-towards ACTH (Ka=1.136+/-0.042 microM(-1)). The lower amount of Zn(II) associated by the studied peptide, the higher was its affinity versus this metal (r=-0.942). The analysis of the kinetics of the Zn(II)-peptide linkage revealed that the most stable complexes with this metal were formed by GnRH (Kd=0.006+/-0.001 microM(-1)) and by dalarelin (Kd=0.020+/-0.001 microM(-1)). Zn(II) with GnRH complexes are about 147 times more durable than ACTH (Kd=0.880+/-0.033 microM(-1)) ones. It was established that the Zn(II)-peptide complexes were more stable in the case of lower molecular weight of the peptide (r=0.963), and the inferior number of the amino acid residues accessible in the peptide (r=0.967).
Department of Applied Pharmacy and Drug Technology, Silesian Medical Academy, ul. Kasztanowa 3, 41-205 Sosnowiec, Poland. zekfar@infomed.slam.katowice.pl
Barbara
B
Dolińska
Florian
F
Ryszka
D010455:Peptides / Q000138:chemical synthesis / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D013535:Suspensions; D015032:Zinc / Q000737:chemistry / Q000378:metabolism*
D010455:Peptides; D013535:Suspensions; D015032:Zinc