Conformational analysis of the N-terminal sequence Met1-Val60 of the tyrosine hydroxylase

Molecular mechanics method and molecular dynamics (MD) simulation techniques are used to study the behavior and the effect of the amino acids substitution on structure and molecular dynamics of the specific portion of Met1-Val60 amino acid residues from N-terminal regulatory domain of the tyrosine hydroxylase (TH) and its mutants in which the positively charged arginine residues at positions 37 and 38 were replaced by electrically neutral Gly and negatively charged Glu, and serine residue at position 40 was replaced by Ala or Asp residue. Our study allowed us to make the following conclusions: (i) the higher conformational flexibility of the Met1-Arg16 sequence is revealed in comparision to other part of the N-terminus; (ii) the stretch of amino acid residues Met30-Ser40 within the N-terminus forms β-turn so that two α-helices (residues 16-29 and residues 41-60) are paralel one another; (ii) the significant differences that are observed for the Arg37→Gly37, Arg37-Arg38→Glu37-Glu38 mutant segments indicates that the positive charge of the Arg37 and Arg38 residues is one of the main factor that maintains the characteristic of the turn; (ii) no major conformational changes are observed between Ser40→Ala40, and Ser40→Asp40 mutant segments.