THE TOTAL SOLID-PHASE SYNTHESIS OF THE GA MMA-SUBUNIT OF CGMP PHOSPHODIESTERASE FROM BOVINE RETINA AND SOME PHYSICOCHEMICAL PROPERTIES OF THE SYNTHETIC PROTEIN

The 87-membered polypeptide with the sequence of the gamma subunit of cGMP phosphodiesterase from bovine retina rods (PDE gamma) was synthes ized by the solid phase method, Two synthetic approaches, which were b ased on the Boc/Bzl-strategy, were used; both syntheses were carried o ut in a continuous-now reactor with swellographic monitoring. In the f irst approach, five Arg residues were coupled in the form of Boc-Arg(Z )(2)-OH and the final cleavage of the peptide from the support was eff ected by the mixture of CF3SO2SiMe3 and thioanisole in trifluoroacetic acid. There resulted a heterogeneous, ornitine-rich, and absolutely i nactive peptide material which was insoluble in aqueous alkali. In the second approach, Arg(Tos) and the HF low-high cleavage procedure were used, which resulted in a homogeneous polypeptide (according to HPLC and capillary electrophoresis) that manifested correct molecular mass under ion-spray mass spectrometry and the full functional activity cha racteristic of the native protein. The effect of zinc salts on the PDE gamma fluorescence in solutions and on its solubility was established . This demonstrated a significant PDE gamma affinity with Zn2+ ions an d appeared to be connected with the functioning of the protein in the retina cells. For the first time, the dynamics of the peptidylpolymer swelling in different solvents was studied during the synthesis of pep tides with very long sequences.