PSH
ACETYL SERYL TYROSYL SERYL ISO LEUCYL THREONYL SERYL PROLYL SERYL*GLUTAMINYL PHENYL ALANYL VALYL PHENYL ALANYL LEUCYL SERYL SERYL VALYL*TRYPTOPHYL ALANYL ASPARTYL PROLYL ISOLEUCYL GLUTAMYL LEUCYL LEUCYL*ASPARAGINYL VALYL CYSTEINYL THREONYL SERYL SERYL LEUCYL GLYCYL*ASPARAGINYL GLUTAMINYL PHENYL ALANYL GLUTAMINYL THREONYL GLUTAMINYL*GLUTAMINYL ALANYL ARGINYL THREONYL THREONYL GLUTAMINYL VALYL*GLUTAMINYL GLUTAMINYL PHENYL ALANYL SERYL GLUTAMINYL VALYL TRYPTOPHYL*LYSYL PROLYL PHENYL ALANYL PROLYL GLUTAMINYL SERYL THREONYL VALYL*ARGINYL PHENYL ALANYL PROLYL GLYCYL ASPARTYL VALYL TYROSYL LYSYL VALYL*TYROSYL ARGINYL TYROSYL ASPARAGINYL ALANYL VALYL LEUCYL ASPARTYL*PROLYL LEUCYL ISOLEUCYL THREONYL ALANYL LEUCYL LEUCYL GLYCYL THREONYL*PHENYL ALANYL ASPARTYL THREONYL ARGINYL ASPARAGINYL ARGINYL ISOLEUCYL*ISOLEUCYL GLUTAMYL VALYL GLUTAMYL ASPARAGINYL GLUTAMINYL GLUTAMINYL*SERYL PROLYL THREONYL THREONYL ALANYL GLUTAMYL THREONYL LEUCYL*ASPARTYL ALANYL THREONYL ARGINYL ARGINYL VALYL ASPARTYL ASPARTYL*ALANYL THREONYL VALYL ALANYL ISOLEUCYL ARGINYL SERYL ALANYL ASPARAGINYL*ISOLEUCYL ASPARAGINYL LEUCYL VALYL ASPARAGINYL GLUTAMYL LEUCYL VALYL*ARGINYL GLYCYL THREONYL GLYCYL LEUCYL TYROSYL ASPARAGINYL GLUTAMINYL*ASPARAGINYL THREONYL PHENYL ALANYL GLUTAMYL SERYL METHIONYL SERYL*GLYCYL LEUCYL VALYL TRYPTOPHYL THREONYL SERYL ALANYL PROLYL ALANYL*SERINE

Tobacco Mosaic Virus, Dahlemense Strain.
This word has appeared in the American Chemical Society's Chemical Abstracts and is thus considered by some to be the longest real word.