The greatest buffering capacity at physiologic pH would be p

Discussion in 'USMLE STEP 1' started by Guest, Feb 28, 2011.

  1. Guest

    Guest Guest

    The greatest buffering capacity at physiologic pH would be provided by a protein rich in which of the following amino acids?

    A. Lysine
    B. Histidine
    C. Aspartic acid
    D. Valine
    E. Leucine
  2. Guest

    Guest Guest

    Valina is the answer

    The structure of myoglobin is illustrative of most water-soluble proteins. Globular proteins tend to fold into compact configurations with nonpolar cores. The interior of myoglobin is composed almost exclusively of nonpolar, hydrophobic amino acids like valine, leucine, phenylalanine, and methionine. In contrast, polar hydrophilic residues such as arginine, aspartic acid, glutamic acid, and lysine are found mostly on the surface of the water-soluble protein.

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