6.2 The role of the sequence in Protein structure All ofthe information necessary for folding the peptide chain into itsnative structure is contained in the primary amino acid structure of the peptide 级结构决定高级结构
6.2 The Role of the Sequence in Protein Structure All of the information necessary for folding the peptide chain into its "native” structure is contained in the primary amino acid structure of the peptide. 一级结构决定高级结构
How do proteins recognize and interpret the folding information? Certain loci along the chain may act as nucleation points Protein chain must avoid local energy minima Chaperones may help
How do proteins recognize and interpret the folding information? • Certain loci along the chain may act as nucleation points • Protein chain must avoid local energy minima • Chaperones may help
6. 3 Secondary structure
6.3 Secondary Structure
Consequences of the Amide plane Two degrees offreedom per residue for the peptide chain Angle about the c(alpha) n bond is denoted phi Angle about the c(alpha)-c bond is denoted psi The entire path of the peptide backbone is known if all phi and psi angles are specified Some values of phi and psi are more likely than others
Consequences of the Amide Plane Two degrees of freedom per residue for the peptide chain • Angle about the C(alpha)-N bond is denoted phi • Angle about the C(alpha)-C bond is denoted psi • The entire path of the peptide backbone is known if all phi and psi angles are specified • Some values of phi and psi are more likely than others
The angles phi and Amide psi are shown here a-Carbon R Side group Amide planc =180°,v=180°
The angles phi and psi are shown here