The collective normal modes of the hexapeptide -Ser-Cys-Lys-Leu-Asp-Phe-, a fragment of apolipoprotein B (apo B), have been obtained. They reflect the dynamic nature and are atleast partly responsible for energy input in autolytic activity. Further, on energetic considerations based on the measurements reported by Sim & Sim, it has been shown that of the two such fragments only one induces autolysis, while the other remains anchored to the coated pit.