Reprint of: Fluorescence and the Structure of Proteins. I. Effects of Substituents on the Fluorescence of Indole and Phenol Compounds.

The quantum efficiency of fluorescence was measured for simple derivatives of indole and phenol and for tryptophyl and tyrosyl residues in peptides and proteins. Fluorescence of these compounds decreased as the electronegativity of substituents increased. In proteins, one strongly electronegative structure is the peptide bond.

Estimate of methane emissions from the U.S. natural gas industry.

Global methane emissions from the fossil fuel industries have been poorly quantified and, in many cases, emissions are not well-known even at the country level. Historically, methane emissions from the U.S.

Biomolecular absorption of ultrasound: II. Molecular structure.

Measurements of absorption coefficients in several globular and linear proteins yield no correlations of absorption with alpha-helix content or with the number of polypeptide chains in the protein. Removal of all but the primary structure with denaturing agents that convert proteins to random chains causes only small changes in the absorption of globular proteins. Complete denaturing of linear muscle proteins results in large reductions in absorption.

Biomolecular absorption of ultrasound. I: Molecular weight.

Amino acid solutions have absorptions which are generally small compared to those for proteins. Proteolytic enzyme treatment of proteins in solution reduces their absorption. These observations suggest that absorption increases with molecular weight.