The Collaborative International Dictionary of English v.0.48:

Alanine \Al"a*nine\, n. [Aldehyde + the ending -ine. The -n- is
   a euphonic insertion.] (Chem.)
   one of the natural amino acids found combined in the proteins
   of most living tissues. It can be isolated as a white
   crystalline base, C3H7NO2. The natural form is the
   L-configuration.
   [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

alanine
    n 1: a crystalline amino acid that occurs in many proteins