Globular proteins hydrophobic side chains, packing

As the o-helix has 3.6 residues per turn, hydrophobic side chains spaced at combinations of three and four residues apart are required to make an amphipathic structure. For helices in globular proteins, a variety of combinations of three-plus-four spacings of hydrophobic residues are observed (Chothia et al., 1981). This leads to a range of helix-helix packing angles and arrangements. However, to form more persistent fibrous coiled-coil... 

Hydrophobic effect With respect to globular proteins, the stabilization of tertiary structure that results from the packing of hydrophobic side chains in the interior of the protein. 

The hydrophobic amino acid side chains on the exterior of the integral membrane protein interact with the hydrophobic lipid of the membrane exterior and are stable in the nonaqueous environment. These residues pack in the interior, hydrophobic environment of globular proteins. 

The tertiary structure is the complete three-dimensional structure of a polypeptide chain. Many polypeptides fold into compact, globular structures in which amino acid residues that are distant from each other in primary structure come into close proximity in the folded structure. Because of efficient packing, most water molecules are excluded from the protein s interior. It is the different interactions between the side chains of the amino acids that stabiUze the tertiary structure. A major force stabiUzing the tertiary strucmre is the hydrophobic interaction among nonpolar side chains in the core of the protein. 

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