An isolated, water-soluble polypeptide fragment of human tryptophanyl-tRNA synthetase is useful for the inhibition of angiogenesis. The polypeptide has the amino acid residue sequence shown in SEQ ID NO: 7, SEQ ID NO: 12, or an angiogenesis inhibiting fragment thereof, the fragment including at least one of amino acid residue signature sequences HVGH (SEQ ID NO:10) and KMSAS (SEQ ID NO:11). Methods of using the polypeptide to inhibit angiogenesis are also provided.