  Scientists have long speculated about the potential habitability of Venus,
not at the 700K surface, but in the cloud layers located at 48-60 km altitudes,
where temperatures match those found on Earth's surface. However, the
prevailing belief has been that Venus' clouds cannot support life due to the
cloud chemical composition of concentrated sulfuric acid-a highly aggressive
solvent. In this work, we study 20 biogenic amino acids at the range of Venus'
cloud sulfuric acid concentrations (81% and 98% w/w, the rest water) and
temperatures. We find 19 of the biogenic amino acids we tested are either
unreactive (13 in 98% w/w and 12 in 81% w/w) or chemically modified in the side
chain only, after four weeks. Our major finding, therefore, is that the amino
acid backbone remains intact in concentrated sulfuric acid. These findings
significantly broaden the range of biologically relevant molecules that could
be components of a biochemistry based on a concentrated sulfuric acid solvent.
